Audio but no video in some of my purchased movies

I have movie purchases that are in my library but when I try and play them there is no video, just a checkerboard pattern that I usually associate with a transparent layer. When I go to try and re download them, they say "Downloaded" and I can find no way to download again. This has happened for no apparent reason that I can think of other than updating the Apple OS X.

All software is up to date. 24" iMac 2.8 GHz 6GB 3TB 10.8.3 iTunes 11.0.2