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)