[youtube] Modify the regex to match ids of length 11 (fixes #1396)

In urls like http://www.youtube.com/watch?v=BaW_jenozKcsharePLED17F32AD9753930 you can't split the query string and ids always have that length.
Fix the minutes part in FileDownloader.format_seconds (fixed #1397)

It printed for the minutes the result of (seconds // 60)