If you’re just looking for a demo structure, Ubiquitin (e.g. 1ubq.pdb) is a good choice, and Rosetta does reasonably well folding it.
Regarding legalities, you own anything you produce using Rosetta (that is, any structural outputs or analysis results). The license only resticts redistribution of Rosetta itself, not the information and results you produce using Rosetta, or your own creations which are otherwise Rosetta related.
I agree with Steven that there’s not anything a priori I can think of which would restrict you from posting instructional videos about how to use Rosetta, even ones which show example Rosetta input and Rosetta output. I also agree that if you want to confirm details about what you can and can’t do under the Rosetta license, the University of Washington CoMotion people are the ones who have the official say on the matter.
P.S. If you do make a video, be sure to let us know about it — I’d be interested to see what it looks like.
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