If you have installed the latest version of Quicktime, then I'm going to go with Tone on this one and say it sounds like corrupted downloads.
Grab all the rars. They'll let you know if they are corrupted when you start to unpack them.
Although it's really bizarre that all of the downloads would be corrupted.
Don't tell anyone I suggested this and if you do, I'll deny it, but you could try just clicking (instead of right clicking and saving) on the links to see if quicktime will try to play them. Quicktime do the whole play it as it downloads it thing. If it doesn't want to open them, then it is a problem with your Quicktime install. If it does, then you have bad downloads.
I forgot where I was going with this post several times, so if it doesn't make sense, forgive me. I'll edit it in the morning for clarity. I'm tired.
