Video episodes now work fine on Proton Experimental, and apparently even on regular Proton as of the latest update, but I haven't tried it. They are streamed from Microsoft's (poor) servers and can pause to buffer pretty regularly however, no matter how good your internet connection is. Medium settings look good and can net you a pretty stable 40fps with SteamOS built-in cap, but some areas (mostly during non combat scenarios) can drop to the mid-30fps. I advise capping the game to 30fps for a perfectly stable experience if that's what you like, as the motion blur is well implemented and makes the game look decently smooth. Input lag can feel pretty high but that's a quirk of the game itself and feels similar to other Remedy games. Disabling Vsync can help a little with it.