taking content to youtube is only partially usefull: Why make youtube a better backing track place? why would you go visit wikiloops then?
of course, there is a huge crowd out there, so we did share some vids there. Teaming up is a difficult one, too - every website has to live off sales or add placements, so everyone would like to offer you a deal, but sharing valued users? I am still hoping the facebook thing will help in the long run, and since I only started working on the meta-info of wikiloops a few weeks ago, there will be some development in search engine results. I google "free backing tracks" a couple of times a week to see where its at, and there is a little movement already.
What definetly helps a lot is friendly recommendations in forums and boards. thats a bit problematic if you are the site owner and only registered for this purpose, but friendly recommendations on free tracks by long term community-members are really appreciated.
Theese little links left somewhere on music related sites help more than one might think.
What specific upgrades are you looking for? thats always interesting to know :)
sorry bout being negative to the youtube thing, I dont like the idea of giving them rights on too much sound (take a read into the YT-standard-license some time).

thanks for all input, as always :)