Sounds like there are bigger issues with the device. I don't have to reboot JUST to watch a video stutter free WITH audio EVERYTIME. Very rarely do I have to reboot due to audio not working PROPERLY on my Surface 3. Sometimes it plays, but I can hear a tiny bit of static in the background and a restart resolves the issue for days before the static returns.
Video always plays back smoothly, even at 4K quality, for me. Maybe it's an internet speed issue? I'm currently at 85mbps down and 25mbps up so I don't experience any issues with video streaming. What are your current speeds?