TL;DR: All old YouTube feeds still work in BazQux.

Hi, some time ago YouTube decided to deprecate their RSS feeds (calling it a switch from API v2 to API v3). They left undocumented feeds for users & channels but search, most viewed and subscriptions feeds were completely removed.

It's unfortunate trend when services remove RSS feeds. Both Facebook and Twitter have removed them, Google+ did not bother to have them at all.

What they don't understand is that people who used to reading via RSS reader don't start visiting website if you remove RSS feeds. They will just abandon it.

Another thing they don't understand is that API doesn't help casual user. RSS allows automation that non-programmer can use. Just put your feed into IFTTT, Zapier, Yahoo! Pipes, you name it, and do anything you want without writing a line of code.

Removing those "outdated" XML RSS feeds in favor of shiny new JSON APIs is like replacing e-mail with the next chat app. Some people just prefer e-mail.

But enough complaining.

All old YouTube feeds are still supported in BazQux Reader (calling YouTube API v3 internally).

And you can directly subscribe to YouTube channels, users, playlists and search by pasting their URLs.

There are few more old feeds that don't have direct analog on YouTube site so you need to know their format to subscribe in BazQux.

List of new videos from user subscriptions (BTW, it required a lot of API calls to implement it):
http://gdata.youtube.com/feeds/api/users/USERNAME/newsubscriptionvideos
If you get 403 errors please uncheck "Keep all my subscriptions private" in YouTube privacy settings.

Most popular videos today (you can replace US with any other 2-letter country code):
http://gdata.youtube.com/feeds/api/standardfeeds/US/most_viewed

Related videos:
http://gdata.youtube.com/feeds/api/videos/VIDEO_ID/related

And just for the history (all these feeds still work in BazQux too but it's easier to copy address of YouTube page than to edit these templates): 
http://gdata.youtube.com/feeds/api/users/USERNAME_OR_CHANNEL_ID/uploads
http://gdata.youtube.com/feeds/api/users/USERNAME/favorites
http://gdata.youtube.com/feeds/api/videos?author=USERNAME_OR_CHANNEL_ID
http://gdata.youtube.com/feeds/api/videos/-/SEARCH_KEYWORD1/KEYWORD2/…
http://gdata.youtube.com/feeds/api/videos?q=SEARCH_KEYWORD1+KEYWORD2+…
http://gdata.youtube.com/feeds/api/playlists/PLAYLIST_ID
/feeds/api can be replaced with /feeds/base or even just /feeds
gdata can be replaced with www

These feeds are new semi-official feeds (but they're also handled via API v3 in BazQux to show video duration and formatted description): 
https://www.youtube.com/feeds/videos.xml?channel_id=CHANNEL_ID
https://www.youtube.com/feeds/videos.xml?user=USERNAME
https://www.youtube.com/feeds/videos.xml?playlist_id=PLAYLIST_ID

All these YouTube feeds, Twitter accounts, lists, searches, Google+, Facebook and VK pages. They're all supported in BazQux. Hope it helps you to see more interesting content instead of browsing dozens of sites everyday.