I think I am confused. What is the "1" for in all three URL schemes? Is it used to identify the collection ("the 1st collection"), or to refer to the position of the media in the collection ("the 1st media in the collection")?

Would the following scheme be alright?

http://gmg.example.org/u/user-name/m/media-name/c/collection-name/

Also, I seems to recall that a collection can consists of media drawn from different users. Would this complicate things?