Optionally filter out crap videos, based on votes

A certain number of videos in Best Of are crap, as show by low scores from viewer votes. When watching via "Play from here" it'd be handy to skip videos that fall below a user specified score.

This change achieves that by allowing the user to specify a minimum score and a vote threshold. Any video with more votes than the vote threshold AND a score less than the score minimum will not be listed.

The vote threshold is necessary because a video just a handful of votes won't always have a score that's representative of what people think of it. 

The default vote threshold is 10.
The default score minimum is 0, i.e. by default all videos are listed.