[mythtv] cutting still leaves unwanted start/end frames

[Chris Petersen]

ok, I'm looking back on some of my recordings and it really looks like 
the first and last frames have been kept, instead of cut (I remove the 
first/last markers just to make SURE that no frames at the start/end are 
left).  Why not just replace those frames with black/silence instead of 
using them?  It would be a LOT nicer/cleaner.

-Chris