Replace the hardcoded flv with determine_ext. Let rtmpdump parse the url.
Make id group non-greedy so that .html is not included in it.
[youtube] Construct a playlist URL in case the page is missing one
This fixes jumping from user/channel -> playlist for some users like https://www.youtube.com/user/BitcoinFoundation This also removes the superfluous log message "add --no-playlist to just download video VIDEOID" when downloading a user/channel.
Thanks to @brickleroux for finding out the problem