Using the latest drivers on my r9 295x2 the video settings have no effect on videos at all. Amongst all the other r9 295x2 problems with windows 10.
I just tested and this was working on my system.
1. Enable Demo mode
2. Download a video to watch on windows media player
3. Set vivid as a profile
4. Watch the video and you can see a red line down the center of the screen showing the difference between the default profile and vivid.