Looks like I was lucky enough to be a beta tester for the future YouTube interface. The video player itself has not changed, but the “binding” has changed a lot, and it is still changing. More recently, for example, he began to localize, and not always successfully :) Because Google clearly did not ask me not to show this interface, there will be several screenshots under the cut.
The main interface has become much cleaner. All the excess was hidden under the drop-down panels:

The “other videos” of the user were hidden in a convenient scroller above the video:

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Information about the video and customizable pieces for insertion on the sites, too, hid in a folding bed:

The comment control panel now pops up when you hover the cursor:

Each video in the list has a context menu. While in it only adding to the queue:

The queue / list widget itself is now smaller and has graphical playback and transition switches. True with the localization did not hit:

And the most important thing is the change in behavior in the search. Now the new search does not interrupt the currently playing video, but only pushes it to the side:

So, probably, a new, more convenient YouTube is waiting for us soon.