After the fuss over the baked-in DRM of the new unibody MacBook, Apple has updated QuickTime to re-enable standard definition playback on many external monitors, including some of Apple's own.
The new Mini DisplayPort connector on both the new MacBook and MacBook Pro supports HDCP, a "feature" which stops people playing tagged video content on non-compliant monitors or projectors. The heavy handed implementation meant that some people couldn't watch certain (seemingly random) movies from the iTunes Store itself except on the notebook's built in display.
An update to QuickTime (7.5.7) is now available to fix this. While HD content is often protected this way, standard-def usually isn't, and that's what the update corrects. You should be able to play any of your SD movies and TV shows on a regular VGA monitor and likely on DVI displays.
This is good news for teachers wanting to watch Hellboy 2 during the lunch break (advice: don't bother -- it's terrible), but clearly shows that Apple has opened the "bag of hurt" that is movie copy protection. So, either get used to watching HD movies on a small screen, buy a brand new monitor or pay a visit to the Pirate Bay. Like most people, I expect you'll be driven the the last option. The fix will show up in unibody Mac's Software Update.
QuickTime 7.5.7 for DisplayPort Allows Standard Definition Playback [MacRumors]
