Windows XP sp3, Mozilla Firefox version 44.0.2, Flash version 20.0.0.306; Try to watch sny videos on You tube site and the video starts and stops and sometimes stops for minutes before starting again, and also when it does run the audio and video of

Honestly, it's time to upgrade to a modern version of Windows.  Beyond catastrophic failure, we're not going to make significant investments in improving Windows XP support.  I doubt our browser partners are making significant investments at this point, either.  You can buy a Chromebook for $200, and great little Win10 machines for $400. 

You can try working through the video troubleshooting guide, but beyond that, I don't have a lot of good suggestions.  We're not even allowed to possess a WinXP machine in any of our offices at this point because of the inherent security issues.

You can find the video troubleshooting guide here:

https://helpx.adobe.com/flash-player/kb/video-playback-issues.html

If you're still stuck, please follow the directions in the guide on providing the dxdiag report and additional information about what you tested and saw.