I just tried it out, and it works just fine here in Firefox on Fedora 32. Since you can see the other person’s video, it shouldn’t be a codec related issue.
Can you try creating a fresh user and testing there if the issue persists?
When I used the Pop!_OS with Nvidia drivers, it worked fine.
I am test driving OpenSUSE Tumbleweed.
1- using the default config, same exact issue.
2- install the NVIDIA drivers (which is STUPID EASY on OpenSUSE), and it works fine.