It would depend upon whether the music one submits is in general or specific demand or "just the sort" of thing that a film maker or promo-maker wants, generically or particularly. Another matter is the nature of the licenses issued and the credits transferred – i.e., is it required that the user credit the author/publisher accordingly.

I did have a brief experience with one such site (half-price membership offered via BMI), which offered, among other arrangements, a "quick license," whereby someone would pay, say $30 to use your piece of recorded music in, say, a student documentary or a porno or an agricultural education video – without having to get your permission or consent as to the nature of the project nor how it would be used in it. I had a number of beefs about the site, its policies, its features, and its functions, so I quit. I also tried an online music-licensing agency, but it became apparent that I was not cut out for whipping up some crapola with a "Black Keys vibe" overnight, so I opted for the kind refund on my registration fee.

Here's the advice that people are always giving me: Keep starting at the bottom, because you have to keep starting - over and over again - somewhere. Throw your talent and hard work away on student films for nothing. Let more successful friends steal your ideas right out from under your nose. Waste a lot of money on CDs sent to college radio stations, as though this were still the '90s. Keep paying membership fees to sites that jerk-off your dreams. You gotta want it badly enough to do stupid things over and over, chasing your tail, and even if you get nowhere and people say, "It's just too bad that you can't . . .," but never bother to help, at least you make it incontrovertible that you believe in yourself.

Just kidding. Best of luck to you. Just test the waters before you jump in; survey the landscape before you take off hiking; be sure you always know where the nearest exit is located.