There is so much wrong with this thread. Just about every single post I could call someone out on something. Instead I'll just explain everything in great detail.
Sampling is taking segments of or full songs and using them in a song that you create. For example, acapellas, melody lines, drum hits, ect. Sampling does NOT include the actual score. If done right, video game remixes are fine because they are NOT sampling. They are recompositions. But let us consider video game remixes as unacceptable. Then shouldn't covers be as well? They aren't even recompositions. They're the exact same track just played by someone else. However they are acceptable. So long as proper credit is given, they are fine.
On the topic of sampling and remixing, using samples that are released under the Creative Commons license are fine. This can sometimes be skewed and a mod may say "but the rules say that no copyrighted samples may be used." However, if the artist, such as Trent Reznor of NIN, release there songs to be remixed freely by whoever wants to, then they are allowed to submit those songs here. The licensing terms make it completely legal. This isn't that case for all songs though. Though there are some situations like the one above, often time artists allow people to remix there songs for contest run by them and can only be submitted to certain places. If that's the case, then no it's not allowed.
There is one more instance that I'm not sure about myself and would like an answer to, and that's if you buy the separate pieces of the track for remixing. A few months ago Radiohead released a song called Nude. Along with it they allowed listeners to buy the separate tracks to the song for remixing. If a person were to buy them and remix them, would they be acceptable to post on Newgrounds?
Any instances of sampling other than what was stated above and drum sampling is strictly prohibited. Some people such as SadSpoon may say "oh but don't you break the law in real life?" First of all, not all people are irresponsible. Second, I'm sure that you wouldn't have a multi-million dollar lawsuit against you if you did that would also bring an end to not just you, but an entire community.
Speaking of which brings me to my next point. In real life, when you break the law and are caught, you suffer the consequences, whatever they may be. Those who enforce the law are the police. Now let's apply this scenario to Newgrounds and change laws to rules. When you break the rules of submitting to the Audio Portal, the Newgrounds police, more commonly known as 'mods', will respond. Just like in real life, you will suffer the consequences, which happens to be deletion.
Honestly guys, learn to deal with punishment. It's really pathetic.