@zauxst,
Thank you for reaching out.
Testing this on macOS and Windows 10, I’m not seeing any issues with having more than one YT video play at the same time. In fact, while it gave me a headache while testing :p, I was able to open 5 different videos all playing at once without any issue.
Can you elaborate a bit on the scrolling portion of this that you describe towards the end of the issue? Is this integral to producing the issue? If so, can you include it in the steps to reproduce so that I can follow your steps exactly and attempt to produce it on my end?
Thank you