Playing videos and streams in VRChat on Proton

Problem

Video players cannot be played in VRChat on Linux. Or, videos can be played, but RTSP/RTSPT (real-time streaming) cannot be played.

Solution

Use GE-Proton or GE-Proton-RTSP.
If you only want to play videos, GE-Proton can handle it, but since it does not support RTSP, it's recommended to use GE-Proton-RTSP unless you encounter any issues.

Using ProtonUp-Qt

For GE-Proton, you can easily add it via the Add version button at the bottom left.
For the RTSP version, enable About -> Enable advanced mode at the bottom right, and then add it in the same way as GE-Proton.

After adding it, restart Steam completely, and you can select the added Proton version in VRChat -> Properties -> Compatibility -> Force the use of a specific Steam Play compatibility tool.