Just today, I started getting this weird error message when trying to play videos on my computer that are embedded in a web browser. I'd try to start it and the thing would just sit there, and eventually I'd see the error message: If playback doesn't begin shortly, try restarting your device. This was with every browser and even with a new user.
Well, it turns out that the audio device on this machine was messed up. I'd somehow managed to break that setting. Fixing it allowed the video to start.
Thanks to this page for the clue. Posting this in the hope it might help someone else.
