The extension Magic Actions does this for YouTube. I don't know about other websites.
Yes I know. I know this extension , I use it from Opera 15 (on 12.50 ExtendTube 😉 )
The problem is on the other sites.
Is it possible, is it any way?
Not that i know of. There are some
extensions that can do that for some specific pages.
Just as I suspected, html5 is a step backwards.
Autoplay is one of the worst thing of user experience on internet!
I have to agree too.