So the projector thing isnt from DXVK, but rather from the Windows Media Foundation library. Basically, there are a bunch of video codecs that are completely illegal to reimplement locally because of the patents on them.

The good news is that Valve is working on a major workaround, and just pushed it out to Proton Experimental recently. They’ve had okay-to-good support for video codecs up until recently (right around after you had that problem), and now it should be moving towards great-to-perfect.