YouTube videos randomly buffer infinitely

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For at least 4 months I've had a problem where I can only watch YouTube videos for a few seconds before it starts to buffer infinitely, even if the next 3-4 minutes of the video have already been loaded/buffered. Sometimes I can "fix" it by clicking the timeline at a different timestamp (e.g. a second later), but it will likely get stuck and buffer again after a few seconds.

I've noticed that this happens more often the more recent the video is. E.g. a video uploaded only an hour before I watch it will get stuck after 5-20 seconds, while videos that are days or weeks old may not get stuck at all.
The same videos play perfectly fine in Chrome.

The same bug plagues my brother's computer, and it seems that it is fixed by turning of hardware acceleration (it worked for him, I haven't tried it since I don't want a video to eat 50+% of my CPU). We're both running Windows 7 x64. I have an AMD gfx card, and he has an nVidia card.

(I have posted a bug report, but I felt like it might be worth posting here as well to see if others share these problems.)

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@Gwen-Dragon Yes, that's my bug report. Speaking of which, apparently Vivaldi's "auto-fill forms" feature added my physical home adress to the "Website where the bug occurs" field. It should be YouTube, of course, and not my house.

ETA: Will give #ignore-gpu-blacklist a shot.