Screen video capture software need some tricks if you want to record in high quality:

• You need a 2-PASS encoding to get smaller files. But you can't capture from your screen using a 2-pass encoding!
• For the best quality it is recommended to record using HUFFYUV lossless codec first. Huffyuv provides very good quality, but generates a data stream of 10-15 MB/sec.
  
  If your hard drive is not fast enough then you may use a MOTION JPEG codec: Morgan MJPEG, PICVideo MJPEG, MainConcept MJPEG. Motion JPEG codecs generate data stream of 3-8 MB/sec while providing good quality.
• After that you may compress your Huffyuv or Motion JPEG recordings using MPEG-4 AVC codec (like x264) or MPEG-4 ASP codec (like Xvid) and a 2-pass encoding method.
• It is usually a good idea to convert WMV to WMV, RM to RM, .MOV to .MOV, .FLV to .FLV (Windows Media to Windows Media, Real Media to Real Media, Flash video to Flash video) to have less quality loss.
  
  But you can test other codecs as well. For example: free x264 or free xvid.

One of our favorites you can try is Replay Video Capture. It records from screen using MPEG-2 or Windows Media codec and I'm very satisfied by its quality.