I do not think Tom his saying no more copyrighted content period, just if you want any spotlight on Newgrounds, you are going to have to be more original, because that puts a serious damper on "just for fun" projects, or new animators who always wanted to make a music video/parody.
Ever since I came to college, Newgrounds has been my source for music since more non-techno/DNB/trance stuff has gotten more popular.
However, I still find myself going for sound effects ripped from video games, movies, etc. I do not mean things like light sabers or DBZ Super Saiyan sounds, but punches, kicks, glass breaks, etc. because I did not have to pay, they are high quality, and I BELIEVE if they are not that distinct they are fine to use, unless I am mistaken?
I have seriously thought about buying royalty free sfx though...