I don't think this is a AD setting issue. I have set the screen saver to a 1 minute timeout and when running VLC, the screen saver doesn't start. However, when runing a video in MC14, the screen saver will continue to interrupt.
Right, I did some testing with this and it seem that setting the AD GPO settings do make a difference. The policy that does it is:
User Config --> Policies --> Admin Templates --> Control Panel --> Display -> Screen Saver = Enable
The odd thing is that this only appear to cause an issue when the "Password protect on Resume" setting is enabled, either via gpo or manually.
The really odd thing though is the VLC doesn't have a problem with any of this, so what every they do, theu must disable the screen saver in a slightly different way