Here's one of the best rendering guides for youtube use that is available -> http://premoguild.com/forums/showthread.php?t=6048
Key points are:
- you capture and renderer at same fps, for example 30 on both, do not use 29.97 or other silliness
- square pixels aspect ratio
- progressive frames, never ever interlaced
- when saving the video out from editor, use 2-pass encoding and about 10000kbps bitrate, that will give you 800meg video next time instead of 3GB
- right codec/video format to use when saving 1080p is either h264, avc or wmv