I don't have any flashblocker installed. I thought it was because of HTTPS Everywhere but I disabled it temporarily and got the same result. Anyway I won't add

I don't have any flashblocker installed. I thought it was because of HTTPS Everywhere but I disabled it temporarily and got the same result. Anyway I won't add an exception rule to HTTPS Everywhere for YouTube. So I have no clue at all what the cause could be, I don't think a "it doesn't work for me" bug report would be of any help.