Problem viewing some video files

Question

I get this problem only with some video files, not all. They are all .mov files so it's hard to tell what is causing it. What it looks like is that the video and sound plays but the video is "barred out" with thick white stripes so it looks like three is only 1 pixel size width of video showing through. almost like this:
"menu bar here"
Just pretend with the dotted lines, you can see the video in it's place. I tried reinstalling quicktime but it does not work. Any ideas

Answer 1

It seems I have two networks available at work, one is behind our firewall, and I login to it. This is the network that I can't view streaming video. There is also a "Guest" network that I don't need to login to. This one works with the YouTube and the news site videos.
Thus, I conclude there is a setting that WiFi network administrators can invoke that specifically can block streaming video on some protocols (whatever the ipod touch uses) and not others (whatever the Macbook uses). But the same router hardware supplying the Guest network does not block these protocols. Presumably this has to do with security on one side of the firewall(?)
Anyway, apparently outside of the WiFi controls available in the ipod touch settings.
Weird...
Paul