OK so my question is, Why are so many videos I watch/download from the internet so offset with its audio? Is there a technical reason for that?

Don't rag on me for watching the videos on the internet and say "you get what you payed for" type crap. There are some movies you just can't get on dvd easily to watch whenever you want like DBZ:History of Trunks.

This audio problem seems to happen on every site with many videos at some point or another. would it be my computer?? would it be the site? or the initial uploader? or some mechanic that I don't know?