Ref 1 - OK, thanks for the information
Ref 2 - Nothing makes me think that the laptop entered a low power state when playing over WiDi - I was making the observation that, since the laptop is smart enough to disable all power saving when playing over an HDMI cable when on battery, it should also be smart enough to disable all power saving when playing over WiDi.
Ref 3 - as a test, I enabled WiDi logging and attempted to play an HD video from the laptop (on mains power) to the TV. The video played perfectly to the TV for a couple of minutes and then the connection was lost. WiDi log attached.
Please let me know if, based on the attached log, there is some more troubleshooting I can try.