games that use h264 codec need to have codec support unlocked for it, If you runt his in your terminal once, videos should play on upstream proton `steam steam://unlockh264/`
Follow-up with a separate root cause for one-shot (non-looping) clips. This is not the winegstreamer caps issue above. The game opens its end-of-game cinematic with the playback rate already 0 (Electra/Media Foundation o...
Version details from the affected install (Proton Experimental 11.0, game 2300840, SteamLinuxRuntime_4 / pressure-vessel sniper 3.0.20260805.254768): The gst plugins in the failing path are bundled in Proton itself: `fil...