[mythtv] mythtranscode, key frames and fifo output

[Chris Petersen]

> Actually they don't, mythtranscode has it's own code for skipping the
> frames in the cutlist, so I assume if there's a bug it's in there
> somewhere.

ahhh....  well that explains it, then.

Let me know if you need me to test anything.  My latest encodes have 1-3 
second chunks of commercial left in, and it's seemingly difficult to cut 
them out (avidemux couldn't do it without loss of sync).

-Chris