it's an iframe which this is it's ID
id="watch7-playlist-tray-mask"
Temp Fix
If you use developer tools you can delete it, or hide it.
But this is annoying since you'll need to do it too often.
More Permanent Fix...
If you are running adblock you can click on the badge for it and click "Block an ad on this page" and then click the top right area and just block it out or the whole top bar if you are feeling crazy.
More Permanent Fix Directed
Right Click on adblock –>options –>
goto customize tab
Click Edit for - Manually Edit Your Filters
add this:
www.youtube.com##IFRAME[ID="watch7-playlist-tray-mask"]
