looks like they already posted a patch to 6.0…
With iTunes 6.0.1, you can preview, buy, and download over 2,000 videos on the iTunes Music Store and sync your music and purchased videos with iPod to enjoy on the go. To watch purchased videos, you must have Mac OS X 10.3.9 or later.
iTunes 6.0.1 features several stability improvements over iTunes 6.
After purchasing music from the iTunes Music Store with iTunes 6 or later, you will also need to upgrade your other computers that purchase music from the iTunes Music Store to iTunes 6.0.1.