Video codec questions

I feel like this is a daft question (although I don't actually know why), but I'm going to ask it anyway:

The audio world has .ogg - its non-proprietary codec. Is there an equivalent in the video codec world?

Also, nomatter how much I read on sites like http://www.videohelp.com/ I am never really sure which codecs give best quality/compression ratios. Does anyone have any information on this?

Ogg is to audio what Ogg Theora is to video.

As for the comparison, all I can give you is this. You could also use the links here to do some comparison.

Excellent information, thanks!