Random video avoids user history
Random video avoids user history

The random video function will now try to 'reroll' the video id if it
appears in the user's 50 or (total length / 2) most recently watched
videos. It will do this 5 times at most, since this is still randomized
and has a small chance for really bad performance otherwise.

mmetro/WeirdSideofYouTube,mmetro/WeirdSideofYouTube,ametrocavich/WeirdSideofYouTube