The digicam capture the video in DV Format which takes 13GB filesize for 1 hour video. But your movies are in MPEG2 format which holds a 3 hour movie in a DVD.
The DV format is designed for editing where the MPEG2 format is for viewing/broadcasting.
If you want to compress the DV video, you can use a MPEG2 Encoder. If you are not going to show the video in any consumer dvd players, XVID/DIVX codec is far better than MPEG2.
If you really want high quality in less size, you can use H.264 or VC-1. But do not store the video in DV format, if you never have to edit the video in future.