Hi, over the time the questions like "how do I determine programmatically the license of this image?" or "who is the author of that video? no, uploader's username is not enough" are asked quite regularly, and probably now it's time to fix this.
Please take a look here: https://www.mediawiki.org/wiki/Requests_for_comment/Image_information On that page, I'm trying to collect the requirements for extension that would address these problems, as well as the ways of implementation. If all goes well, I'd like to start coding in 1-2 weeks.