I thought the problem was solved a few days ago but it is not. I can sometimes see live feed video (but not consistently) but not youtube or other stored video. Curiously, if I go to watch, eg, an archived PBS TV show, I get the commercial but then a green screen instead of the program. Some youtube videos have no picture but do have sound; for others, the sound stutters.
I tried the AMD Catalyst 15.6 driver for Windows 8.1 suggested by the previous respondent and that does not help. In fact, one live video feed I could see before installing that I can no longer see.
any other suggestions are welcome. (I did correspond with someone at AMD but their ideas bore no fruit at all.)