[mythtv] editing frame-by-frame weird in recent cvs

[Chris Petersen]

cvs from 2003.09.28...    When editing out commercials, the "1 frame"
setting is occasionally wacky..   I'll back up one frame, and then go
forward one frame, but it actually skips forward .5 to 1 second.  and
occasionally moving forward/backward with small increments like
frame/second doesn't work right - going forward and then backing up
results in a different frame.  The first one is obviously more annoying,
since it's making it VERY hard to isolate a cut point at a specific
frame.

-Chris