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Hi, I'm Jeff Fisher, and in this video, we're going to talk about how to search for videos using the YouTube API

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A common operation on YouTube is searching for videos

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You search for videos in the API by using the videos feed.

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We specify our search term with the 'q' parameter. You can specify

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You can specify a more complicated search term by URL escaping it.

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There are many versions of the API

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which we can specify which version we want to use using the 'v' parameter, or a special header.

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Since there are many cute puppy videos on YouTube, and we don't want to handle them all at once,

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we can specify how many we want by using 'max-results.'

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Since we only want 10 at once, but we might want to page to the next 10,

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we can look at the feed that's returned to the API for a 'link' element with 'rel' equals 'next'

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This will identify the next page of results, and is the proper way of paging through a feed.

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If you look at that 'next' link, you'll notice it has a 'start-index' parameter, which identifies the beginning of the next page

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However, you should not try to set this parameter manually and instead always extract the value of the 'next' link from the feed

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Now let's talk about some other query parameters that you can use with the YouTube API

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First, we're going to talk about 'orderby'. By default, results are returned in order of relevance

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but you can also have them ordered by rating, view count, and the date they were published.

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You can also search for all the videos uploaded by a particular YouTube user with the 'author' parameter.

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This is equivalent to retrieving their uploads feed.

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In version 2 of the API, we added location based search

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where you can pass latitude and longitude information and find videos that occurred near that point.

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Since a large number of videos only have descriptive locations, such as London,

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if you only wish for videos with explicit latitude and longitude information to be returned,

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add an exclamation point to your query.

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To only show embeddable videos, such as for embedding on an external webpage, use the 'format' parameter.

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If you only want results in a specific language, you can use language restrict.

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Note this is only for video metadata, and not the audio track of the video

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You can also specify a safeSearch value which defaults to 'moderate',

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but can also be 'strict' or 'none' for filtering restricted content.

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Some videos cannot be played in certain locales.

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You can specify the locale of your user by passing in their country code or their IP address

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in which case we'll figure out their country code for you.

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Note this is only to improve the user experience, as it will filter out videos they cannot play.

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Using this parameter will not affect the videos that they can play.

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YouTube has a number of video categories, such as Comedy, News and Politics, and more.

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If we only wanted videos in the Comedy category, we can use the 'category' parameter to retrieve them.

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If you are familiar with other Google Data APIs, you can also use the below syntax.

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If you want to do a tag search, you can use the same mechanism, such as searching for all videos that have the tag 'puppy'

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Note that the video category started with an uppercase letter, whereas tags are all lowercase.

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This means that the above search is for all videos in the Comedy category,

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whereas the below search is for videos that have the tag 'comedy'.

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You can also mix and match to combine the different query parameters we have discussed here.

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For example, if you want to query for kitten videos in the Comedy category

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that are embeddable on external webpages, you could use this query.

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YouTube also provides lists of popular videos

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These are exposed in the API as standard feeds.

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Such as the top rated videos, the most viewed videos, and the most discussed videos.

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We can also look at the top rated videos that were uploaded this week using the 'time' parameter.

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We could also look at the top rated videos this month, or today.

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You are also able to look at only the top rated videos in this particular category, such as Comedy.

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Note that this is different from using the 'category' query parameter we talked about earlier.

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The above feed is the top 100 rated videos in the Comedy category.

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Whereas the bottom is -- of the top 100 rated videos on YouTube, which ones are in the Comedy category.

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You can also look at regional versions of the different standard feeds, such as the top rated Comedy videos in Japan.

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Hopefully, you're getting pretty excited about using the YouTube API

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But before you get started, we want to go over a few simple caveats.

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You cannot retrieve more than 1000 videos in a video search feed. This is the same as YouTube.com.

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The openSearch totalResults value is an approximation.

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This is part of why you should not do pagination manually, but instead use the 'next' link.

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Let's go back to our earlier example about searching for cute puppy videos.

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Because YouTube is a large video website, the search information may be cached.

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This means that the most recently uploaded cute puppy videos may not be displayed in the results.

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It also means that the information in these videos, such as the title and description,

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may take a couple hours to be updated in the search index.

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Also, statistics about the video, such as view count and favorite information may not be up to date.

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For videos uploaded as private, and later made public, it will take even longer to enter into the search index.

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What if you know the ID of a video you want to retrieve information on.

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Similar to searching for videos on YouTube, this information will be cached.

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This is also true if you retrieve it through the uploads feed for a user when you're not authenticated as them.

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However, if you do authenticate as them, you will retrieve uncached information, which will be fresh.

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Also, if you retrieve the uploads feed as the user, while authenticating as that user,

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you will receive information about videos that is not cached.

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This means it will the most recent information that YouTube has. It will be ordered by the published time.

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However, if you add a query parameter, such as 'orderby' to this feed,

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even though you're authenticated, the results will be cached.

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Two query parameters that will not affect the caching process, are start-index and max-results,

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so you can still page through a feed.

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If you are using one of our provided client libraries,

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there will be objects and methods which will help you build search queries on YouTube.

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Please check the documentation for these client libraries for specifics.

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All the information in this video is also available in our documentation on code.google.com.

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Thanks for watching!