I only have one more suggestion: uninstall ffdshow and download and install the Gordian Knot codec pack from doom9. This is different from the rip pack which contains the ripping/encoding software. You may have to decline the installation of the newest DivX as it may contain adware. It will also install ffdshow and set it with the proper settings.

It is possible that you are missing a certain codec or are currently using an unsuitable codec for mpeg processing. If that doesn't work then I give up.