I have created a folder that all student's have access to on the Macintosh HD - but the problem is that ALL students have access to this and therefore each other's footage, and they can only work on the one machine.
My solution is once the video has been imported, copy the file into iPhoto from the HD.
It takes a little time, but it adds the mobility from one computer to another.
They can then delete the original movie from Macintosh HD - so nobody else can access the footage.
Hope that helps.
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Maff.