I'm sorry if this isn't really a bug. I looked all over, and couldn't find a full list of forums, so I wasn't sure if there was a separate feature request board.
Anyway, the issue is that, on the old player, I could set a video to fullscreen on my second monitor and continue working on a primary monitor. Youtube has always allowed this, but the current player set to "Progressive" loses fullscreen when it loses focus.
Thanks, keep up the good work.