If you’re going to upload video on the internet, there are four basic ways you can encode that video:
1, you can follow The Scene‘s kind of complicated standards, which are oriented more towards high-quality television and movie material ripped from DVD than anything else; (Very basically, AVI files with XviD encoding and MP3 or AC3 audio.) All other things being equal, this is probably the best option to take, because the standards were devised in such a way that compliant files are viewable on as many systems and players as possible.
2, you can follow the prevailing trends of the pirate anime community, which vary with time and to an extent country; (The trend at the moment is to use Matroska files with H264 video and AAC audio.) If you don’t need subtitle support, or don’t care about really high-resolution video, this is probably a bad route to take, as this format is, though popular, incredibly poorly supported and thus really annoying (and AAC is teh suck.)
3, you can of course just go and do whatsoever you please, but doing anything really non-standard means people are going to piss and moan, so this probably isn’t a great idea, either, especially if your only defense is “I have no idea what I’m doing”;
4, you can create AVI files with the XviD coded and MP2 (not MP3!) audio, which will be playable on just about any device anywhere. If you don’t care about “The Scene” and subtitle support isn’t a deal-breaker for you, this – I would argue – is the best route to take.