I edit video all the time (oh... it's my job!), and I use Handbrake all the time. If you crank up all of Handbrake's settings to the best quality you can, the results are perfectly acceptable. (Not great, but good) Handbrake will let you rip the DVD (or mini DVD, if your Mac has a tray-loading drive) to MP4 format... which you may then convert to something more usably by iMovie or Final Cut.... such as DV or something.
So... the process is possible, but convoluted. But if you're serious about editing your movies, get a Mini DV camera.