This is a great addon, but
Especially the video page that pops up every time on the video page and forces you to "subscribe to my channel".
On that particular page, when I manually clicked on a particular video and tried to play it, there was a pattern of it failing to play.

I'm sure there are a number of factors, but I was able to play videos with manual clicks with this add-on disabled, so maybe this add-on is the problem.