For information, I can confirm. The video resizes frantically back and forth.
I think it’s a website bug though: there’s a scrollbar briefly showing up, and trying it in Firefox, the video does not shake but the scrollbar is there and a little slice of the video is hidden.
By the way, with shields down the ads are not affected (just a little glitch at the start) but then the video proper starts shaking. My guess is, they reserved absolute space for the video but the main video is slightly larger than the ads, hence the strange behavior (handled differently by different browsers).
Update:- checked on Microsoft edge (should have done earlier, but forgot that I had edge on pc), it seems to be the website’s problem and not Brave’s problem. The issue can be closed.