I hate people like that! Lazy mongrels...
As far as I'm aware you should be able to file DMCA against them - even if it wasn't originally uploaded on YouTube. On my
other channel I had some people who had downloaded my videos - stripped them of their channel branding and my voice over - and re uploaded them to their own channel, monetized. I filed a DMCA with YouTube saying that they'd 'Reuploaded my videos' and they were taken down in a couple hours.
YouTube DMCA isn't "YouTube Only" - you still own the copyright to that alternate clip. It would be like someone uploading full episodes of a television program (which people still manage to do however) - it wasn't aired on YouTube originally - but the original content creators could take it down if they wanted.
*EDIT
By the way, RHETT AND LINK!!! YEAH! *cough* Sorry, got a bit excited. =)