Four hundred replies, wow! Now that I think about it, there's really no reason to worry. Music pirating is so widespread that it can't be stopped. If the mods start cracking down on it, people will just leave and post it elsewhere where it will be accepted.
There are plenty of places to post your work, whether it contains copyrighted content or not. So worry not, Newgrounders! Dry your eyes, stand tall and let them know you will not be shaken! You are not the slave, but the master! Your content is what keeps this site going, and if you give it nothing it will die.
"There comes a time when the operation of the machine becomes so odious, makes you so sick at heart, that you can't take part, you can't even passively take part; and you've got to put your bodies upon the gears and upon wheels, and upon the levers, upon all the apparatus and you've got to make it stop! And you've got to indicate to the people who run it and to the people who own it that unless you're free, the machine will be prevented from working at all." -Mario Savio.
Some of the best animations, such as Anime Munters, Stamp on the Ground, and Babylon Hot Nights have copyrighted audio. Consider that next time you hear somebody talking about censoring.