Also can't find a Mac version.
Found a couple with Google:
NoteBurner M4V Converter Plus
Tune4mac iTunes Video Converter
They're not free and I can't vouch for either of them, not having used them.
Note that removing DRM this way isn't legal. According to this site
be done legally by re-recording, but I'm not 100% sure about that and, again, it costs. I saw other re-recording tools via Google, but didn't check them out.
(I used "remove drm from itunes video mac" as the search).