[mythtv] mythtranscode -> avi

[Chris Petersen]

> How slow is do you find avidemux2? I ran a quick test on my Althon 
> 1.4Ghz machine with a 945 meg file. It took about 30 seconds to open
> the file and 2 minutes to resave it.

Took about 4 minutes to open a half-hour show on my dual athlon 1900+
machine, since it wanted to index everything.  I didn't try the non-gui 
options, mainly because I couldn't find them (didn't look very hard).

-Chris