I'm such an idiot...I actually reinstalled opera but I didn't delete everything and I guess some files from opera 12 remained there also.Now I deleted everything that had to do with opera...installed it again and now it works just fine thank you very much leushino!
PS:I'll try and delete those print screens because there's some advertising that I don't wanna do for free lol...So if anyone has a similar problem just delete everything that has to do with Opera and reinstall it

Yes I do...I just disabled it...the same thing...could have something to do with the html5 thing or that java stuff that youtube is using? Because is not only in comments I also can't like or dislike people's comments...pops up the same window I would love to find a way to fix this because I don't wanna switch to Chrome because is slow as hell...

I'm an Opera user for many years now,I used Opera 12 for quite some time because i didn't felt the need to upgrade but yesterday I found out that I can't upload files on soundcloud or bandcamp so I upgraded to Opera 18. All great!Now I can use Opera to upload music on those sites but a new problem came out and is worse than not being able to upload...I can't comment on youtube from Opera