So far the big studios have largely left alone the fan made series (see numerous incarnations of star trek, The Dark Knight, as well as hundreds of my little pony videos and the like as just some examples). Right now they are (rightfully) of the opinion that fan enthusiasm on this level is better encouraged than the slash and burn approach that was made in the nineties when the consumer internet was just getting started.
Now, as long as the fans hold to their end of the bargain and continue to post things free and not turn any profit on them things should remain hunkey dorey... but all it takes is one greedy asshole to upset the apple cart either by selling advertising, or suing the studio or the labels over some "stolen concept" and it will give the big studios an excuse to crack down and further rewrite the laws and have them enforced in their favour.
