"Any" source? I remain skeptical cuz that would be a very hard thing to do. Or at least not easily and would require a lot of handwork per each individual site you want to embed from. I guess that's why the video is 14 minutes long?
The most important thing is: How easy will it be for users to embed stuff? Anything beyond a simple URL copy/paste has proven to be too much of a hassle for most people.