If I were advising them, I would merely state that you are implicitly granting a license to use the content and to make further modfications as they desire. Ownership is not needed.

The whole concept has become obscured. When iTunes launched its music store they said that you own it. Or really? If one owns something they can typically sell it. However that violate sthe EULA of Apple. It is something that we, as a society, are going to have to really figure out. I am just afraid that those with the money are the ones who will win this debate. I am all for protecting IP, however there comes a point when protection can lead to the exclusion of new ideas and innovation. That was why the original copyright was valid for a relatively short period; now with the Disneyfication of IP, who knows when it really ends.