i just re-installed xp on my computer and im trying to get all the codecs i gathered before formatting. its frustrating because ive downloaded a ton today and i still get videos that wont play video some with no sound. i tried nimo's codec pack but i still run into problems.
Anyway. Do you know what kind of video you're trying to play. Are they older or newer? If newer, say Mpeg 4, try grabbing ffdshow. It's a DirectShow decoding filter instead of a true codec. Plays all the new stuff though, 3vid, Xvid, divx, etc.
In laymen's terms (to save myself any embarassment), codecs are different ways to encode videos. Some are better than others, as in, better quality + smaller filesize. Codecs are always evolving and getting better, so yeah.