I'll separate this into 3 parts 1) Capture 2) Codec 3) Compress
1) You can capture video from your screen in many ways with various software. Some of this software compresses while it captures. I have found this to result in poor video, that is still fairly large. I use the free software Camstudio found here: http://camstudio.org/
A few notes on capturing. Under Options>Video Options use under compressor use: CamStudio Lossless Codec v1.4
Set Quality to 70, Set key frames every 40 frames
The next is critical so your audio and video don't get out of sync. Capture frame every 100ms and playback rate: 10 frames/sec
With these settings you get about 60MB/min on a 1024x768 screen.
2) you will probably need codecs to compress and decompress the video. A good all around codec pack is the K-lite codec pack found here: http://www.free-codecs.com/download/K_lite_codec_pack.htm
3) Compression I use the free software Mediacoder found here: http://www.mediacoderhq.com/index.htm
I have found the h.264 format to provide some of the best compression while still retaining quality. Mode should be "quality Based". One of the best file types to be flash. Although wmv will produce a smaller file with almost as good video.
In audio I set it to mp3 at 64Kbps in CBR rate mode and mono channel.
With these setting I get about 50:1 compression so the 60Meg/min becomes about 1.2 Meg/min. Not to bad.
Hope this helps people capture and compress videos.