Video Transmitter Burn in Cycle

Certainly not. Look for the reason of improved performance else where.

What 'obstacles' are near or between sender and receiver which could account for the poor performance in the original test? HVAC, washing machine (any motor/compressor), TV, internet wifi.... even atmospheric conditions can affect the signal quality. Also, other new wiring may act as an antenna and aid the signal.

One trick to improve mobile phone signals in remote areas was to position the phone in the gap of an open car window, with the door open - the frame seemed to boost the signals!