From MEC E-Lines: (Nov 3, 2006)

United maintenance will start a test on the 767 MD aircraft starting this Monday.  The test is meant to address excessive bulb burnout in the 767 MD projector systems, thought to be caused by a power spike from the ground to the airplane. During the test, the video system will not be turned on until inflight and then turned off again before landing.  This will require Flight Attendants to conduct live demos onboard these aircraft and it will be communicated by IBS notification. 

Affected domiciles include ORD. DEN, SFO, LAX, HNL and DCA.

Maintenance requests that Flight Attendants report observations and results via DIS*123 to help address video system reliability.