I think QTPro would be perfect for you. It has simple cut/copy/paste ability (arrows for stepping, cmd-b to zero selection, everything else is obvious), saves reference movies and is feature complete on both platforms (though much more buggy on Win I've heard, for instance no non-ascii character support in file names). I use it constantly for removing commercials from tv caps. It's the fastest workflow I could imagine for that task.
edit: oh yeah, it doesn't capture, but I'm sure there are many options for just capturing, and as long as they don't capture to MPEG or WMV QT should have no trouble with the files