问题
I was wondering if this is available in v3 (I know it's possible with v2)?
I've tried using watch_later as the id and mine=true in a playlist request. The watch_later playlist is not returned in the generic playlists list results when specifying mine=true.
回答1:
Update
As of Sep 12 2016, watch later and watch history can no longer be retrieved YouTube Data API v3.
Original answer (no longer works)
You can get the IDs of you special private playlists with an authenticated request to
GET https://www.googleapis.com/youtube/v3/channels?part=contentDetails&mine=true&key={YOUR_API_KEY}
One of these is your watchLater playlist. Note the playlist id and use it in another authenticated request to get a list of all items on your watchLater list:
GET https://www.googleapis.com/youtube/v3/playlistItems?part=snippet&playlistId={YOUR_PLAYLIST_ID}&key={YOUR_API_KEY}
来源：https://stackoverflow.com/questions/15891357/is-there-a-way-to-get-the-watch-later-playlist-using-youtube-api-v3