[FFmpeg-user] Converting for YouTube

[Randy Kramer]

On Saturday 20 August 2011 07:11:59 pm bouke wrote:
> Nice trick to test, rip both, apply a difference matte on the two clips.
> If you see something else than pure black, there sure is a difference, and
> those are the spots you need to carefully check.

I'm not the OP, but I'm interested but not familiar with the terminology.  Can 
you give a few more clues as to what you mean by:
   * rip (what do you rip, what command could you use)
   * apply a difference matte (what command could you use)

Thanks!

Randy Kramer