I don't have any specific recommendations for a CMS, though I would say that hosting video is a bit advanced and you may be better off having them submit their videos to youtube and adding embedded links.
In order to choose a CMS, one of the best resources I've found is: http://opensourcecms.com
This site offers reviews, but it also offers admin installs of all of the CMS's so you can log in and play with them without having to install them. This is really useful to get an idea of how the interface works.
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Karl Brown
karl%40cs.stanford.edu">karl
cs.stanford.edu
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