One frustration for me in using the Opera Browser lately has been the number of times that youtube and other videos embedded in articles just come up with a black box and no way to start them. The same links work perfectly in Chrome.

I did some research and found that one suggestion is to click on Tools-Delete Private Data.

I just tried that, with a little trepidation. There is a list that you can customise of what is deleted and what is left, but I decided to be bold and just go with the defaults. Opera crashed then restarted with the tabs I had open and amazingly, the video links were there and working.