Free video editor for Mac

Aloha all!

Short version: I want to replace iMovie HD, but find the new version of iMovie unacceptable for my environment. It's replacement needs to be free (or really cheap) and easy to use.

Longer version:
I teach video editing production at a university. For the introductory class, I use little Sony SD palmcorders shooting on DV, and edit with iMovie. This class is more about storytelling than technology, so simple is the order of the day.

I have been using iMovie HD. However, it is (and always has been) quirky. I'd like something that performs a little more consistently, without the crashes, or the special effects that sometimes work, or any of the other shortcomings HD is known for.

But (you knew there had to be one), the new version of iMovie is not acceptable. The editing lab is set up so that each computer has accounts for each class, but not for each student. In my case, the students would be logging in as "Comm 250." Which means, with the current version of iMovie, that all of the videos ever imported or edited under that account are not only accessible, they are sitting right there asking to be used. We offer multiple sections of this class, so multiple students share a computer over a week. Having one student with such easy access to the work of other students just does not sit well with me.

So I need something else. Something with iMovie's ease of use, something that runs on OS 10.5.x, and something that is either free or mighty cheap.

I did a little Googling, but most of what I could find is either discontinued or hasn't been updated in 5 years. So, what's out there that I haven't found?

Mahalo!
Tom G

The difference between theory and reality is that, in theory, there is no difference between theory and reality.