Slashdot ran a story a few days ago, discussing the new audio compression filter YouTube seems to be using on content. Essentially, they’re trying to get everything into a single intensity range to, presumably, make jumping between videos on YouTube a bit more pleasant. However, like anyone who uses a compression plug in for the first time, they’ve over done it. Waaaay over done it.
The fix, until YouTube does something, is to mix in some constant volume high frequency noise, which will get stripped during the bit-compression phase, but which misdirects the audio compressor enough to keep your actual audio safe.
I can sort of understand what YouTube is up against, as this is an issue I struggle with on Media Mill as well. There are lots of things I can do to make really bad videos look and sound better, but those same things will make good videos look and sound worse. You always try to walk the line between both extremes, but you always wish you could do more.