Sounds a little hinkey, sorry I always tend to look for ulterior motives when I see the word free.
Good idea, I think. Give their "EULA" a close read ...
"Of course you have all the copyrights in whatever you create, but by accepting this license agreement in order to use our software, you automatically grant us a license to do anything we can think of with your work, up to and including stage performance. You, on the other hand, can't even distribute your own content without our permission -- not that it's even possible short of reverse engineering our tools.
But of course, if we make any money off your work, we might give you some of it. If we feel like it."
Not kidding, just paraphrasing.