Yes, they are DRM'd, and from what I can tell with the same DRM as the iTunes Music Store purchases (Authorised for play on 5 machines, or unlimited iPods/Apple TVs etc).
Before you go hogwild, also note that unlike songs, you cannot burn them to DVD so they could be played by a DVD player. They can only be played back on authorized computers, iPods and/or AppleTVs as SirCrumpet states. If that's not an issue, then by all means, go hogwild.