Hi, I have a similar problem like this: https://support.mozilla.org/de/questions/1061332 Im on 44.0.2 on Win10 with a NVIDIA 470. The contrast of each video is terrible and after ~5 minutes watching a video (in fullscreen), the player lags for ~5 sec. and the player plays the rest of the video in a normal contrast. Disabling hardware acceleration fixes that problem, but the video itself will not play smooth anymore. Thanks for help!