How Do You Import a DVD into iMovie

I am trying to import clips from a DVD into iMovie HD 6. I downloaded HandBrake, and "ripped" it from that program. However, it rips it as a .mp4 file, which i tried to import into iMovie and it imports for about 30 minutes, then says, "Error Importing: Unknown Error".

Does anyone have a clue how I can get a DVD (that I made a while ago) into iMovie for editing?

Thanks,
Ryan