If you have a Core Ultra 255H, you should be able to use SR-IOV.
SR-IOV will allow you to split the GPU into multiple virtual devices, that you can pass to multiple VMs at the same time.
There is an HCL report confirming it works with the Core Ultra 155U, but it requires applying some kernel patches manually. There is some information in the replies about how to get it working, but the exact steps needed seems a little unclear.
If you want to try and get SR-IOV working, using the R4.3 alpha release might make it easier.
If you are just having issues with video playback on YouTube, try disabling the “ambient mode” in the YouTube player settings.