Half of these exist because I was bored once.
The Windows 10 and MacOS ones are GPU passthrough enabled and what I occasionally use if I have to use a Windows or Mac application. Windows 7 is also GPU enabled, but is more a nostalgia thing than anything.
I think my PopOS VM was originally installed for fun, but I used it along with my Arch Linux, Debian 12 and Testing (I run Testing on host, but I wanted a fresh environment and was too lazy to spin up a Docker or chroot), Ubuntu 23.10 and Fedora to test various software builds and bugs, as I don't like touching normal Ubuntu unless I must.
The Windows Server 2022 one is one I recently spun up to mess with Windows Docker Containers (I have to port an app to Windows, and was looking at that for CI). That all become moot when I found out Github's CI doesn't support Windows Docker containers despite supporting Windows runners (The organization I'm doing it for uses Github, so I have to use it).
I use Debian. Like I said, video is only sometimes choppy. I usually have a few vlc windows open at one time. Something I've learned is that it will use a lot of CPU even if the video is paused. To stop it, I have to manually set the video source to "none" when I pause a video and leave it in the BG.
Or just pause the whole VM. Another great Qubes feature
this has been my experience with it on windows too, so it must be a core VLC thing. if it bothers you, I recommend you to try out MPV. been using it for more than a year, would never go back. If you need more than the on screen controller and key combos, there are quite a few proper GUI players being built on MPV.