I definitely recognize and remember this, but since I have given up zooming on youtube since months back I have unsurprisingly not been bothered by that, but..

I do have a problem that after a (sometimes short, other times long) while of youtube usage, said site becomes unusable such that it gets stuck on "loading" (freezing) for nearly ever whenever I navigate to a new page within that domain. I have tried disabling extensions (while enabling previously disabled one) one at a time, without result. On the other hand, once when this plagued me yet again, I opened new private window and visited youtube (including same pages that the non-private window was stuck in) in it, everything seemed ok, no problem at all. Everything was fluent. Then immediately tried in the non-private window and still same problem there.

Windows: 7 32-bit Home Premium
Opera: 46.0.2597.39 (this problem has plagued me since many versions back, for many months)

I'd like to report that with the build 37.0.2178.32 the bug has now been fixed. Thanks to everyone involved.

That's the case. Thank you for the feedback !

Ok, I installed "Flash Player for YouTube" (https://addons.opera.com/en/extensions/details/flash-player-for-youtubetm/?display=en), and that works flawlessly so far.

I mean Allow, Deny or Ask? Or you are using that option without any exception?

My default option is "Click to play" (which corresponds to "Ask" in Exceptions). My exception for youtube is "Detect content" (which corresponds to "Detect and run important plug-in content (recommended)" in default settings).

So, I'm using "Click to play" as default, and "Detect content" as youtube exception.

(Btw, different terminoligies for default vs exception settings, for same functionality, is counterintuitive, and I feel that noobs can get pretty confused)

Well, i installed an extension to force Flash player on Youtube, ran a playlist and the videos played automatically even without the tab being the focused one.

I tried yet gain and same outcome. refused to start playing until I focused the tab.

Additionally, like yesterday, in order to rule out extension/userscript conflicts, I also allowed DomainUserAgent to run in private mode and then opened a new private window with 2+ tabs. In one tab I went to a random yt playlist, and immediately switched tabs before it had loaded. The outcome was the same: demanded me to focus the yt tab in order to start playing. Also moved the video position to relatively near the end of the video in the playlist, and switched tab and waited. When the video was finished I could see the tab reload, and then I waited and waited and waited... and nothing happened. I again had to switch to / focus the yt tab for the video to start.

May I ask what extension you used to force flash ?

And which option is being used?

As I wrote, I'm using "Detect content", since I only want to autoplay main videos and not ads and such.

Just as a curiosity: why use Flash?

Although I would love to dump flash and rely on html5, the fact remains that html5 playback is kept not particularly optimized for older hardware. Playing 720p with html5 vs flash is a big differerence, almost twice the CPU usage. FWIW the flags enable-platform-accelerated-video-decoding and disable-accelerated-video-decode are set appropriately. I think those are for html5 video ?

AFAIK that flag doesn't affect Flash.

So it seems. But unless it's flash player itself that does that (which I doubt, not sure, but doubt) I would expect the behavior based on the flag to affect flash player as well.

Well, using the html5 player there is no need to go to the tab for the subsequent videos to play on a playlist. I guess it should work the same for Flash.

Yes, it should work the same for flash, but doesn't. And as I wrote earlier, I use flash because it takes almost half the CPU usage compared to html5 as far as my old(er) hardware is concerned. I have no choice but to switch to ff tomorrow or so until this is fixed.

OK, googling I found the solution, which is hidden inside the flags page (opera://flags or chrome://flags) instead of settings.

1. Navigate to: opera://flags/#disable-gesture-requirement-for-media-playback
2. Click "Disable" in the highlighted entry
3. Restart Opera

EDIT:

It's not working for me; I still need to switch to the tab...

I'm using plugin exceptions' new "Detect content" option (where the other options are Allow, Ask, and Block) for youtube, and using DomainUserAgent extension to force flash plugin in youtube. This new setting "Detect content" is really nice, and saves me the trouble of writing an extension to, if possible, overriding the browser's settings and playing youtube playlists without considering the aforementioned settings, for the purpose of music playback.

However, there is an obstacle that's getting in the way of the playlist playback (note that I'm referring to flash player, which is a plugin, as opposed to html5): the tab needs to be focused for the playback of each video to start. This of course means that playing a playlist you constantly need to switch to the playlist tab for each and every video to start. Is there a way around this, preferably without yet another extension ? Thank you !

No it was not reported there since I, due to experience with other software bug reporting sites, assumed you would need another account and hence never bothered taking a look. Since it doesn't LOOK like it needs (another) account I will do that later and see.

I don't know exactly when it started to happen, but as I wrote in OP somtime before version 35.0 I think. That cannot be design, not sensible one, because it makes no sense for the designer to assume that I want to scroll down to the speedial's vertical center when I close a group popup. I'm sure you agree with me. This obvious bug or illogical design forces me to scroll up again each time I (open and) close a group. Thank you for the reply!

Another update and problem still persists; after closing a group popup window, the speeddial is "scrolled" down to the middle. I also notice that the word "goup" I requested to be fixed, hasn't been fixed. Thank you very much!