nothing, I can't play the HTML5 videos neither... help!!

Mmm unfortunately nope, I checked that option yesterday and according to youtube I'm not using the HTML5 test mode...

But only for curiosity I'm going to enable that option, maybe I could see the videos in the HTML5 mode.

Anyway I'm still open to any advise to fix this problem.

If I right-click the black square, the menu that appears is the same that the right-click menu of any other place in the page

http://tinyurl.com/d8b2smb

It's a little weird but I can play and see all the embedded youtube videos from any page. But if I try to see a video directly in youtube only appears a black square in where it supposed the video must be played.

The only way that I have to see a video in youtube is to change the URL, deleting the "watch?v=" part and writting "embed/" instead.

For example, if I want to play this video

http://www.youtube.com/watch?v=04mfKJWDSzI

I need to modify the URL by this

http://www.youtube.com/embed/04mfKJWDSzI

I have this problem only with Opera and only with youtube.

Anyone have the same problem? Any suggestion to solve it?

Ubuntu 12.04 @ 64 bits
Opera 12.15

Thank you very much