Well, I suppose this is a bit of hard one because of the word backup. If you took the word backup to literally mean a duplicate copy, then the only way you could save space while keeping identical video quality would be to put the backup in an archive with a high compression ratio, but from experience this is very time-consuming and the results are negligible.
However, a RAW video format does seem like overkill. I don't know what the video is, or how you use it but you could probably convert it to something like the xvid codec without compromising the quality but it'd save a lot of space. You could at least convert it for the backups, and if you wanted to go further I believe H264 is one of the smallest, high quality codecs.
If you are going to convert your videos I'd recommend Borrosoft Video Converter, which is what I use and it is brilliant because it will deal with almost anything you throw at it. However, another thing to consider is that on my quad core computer (latest i7 processor) with 6GB of RAM and a 2GB graphics card, you're probably looking at a good hour and a bit to convert a 1 GB video! It's not fast, and it's not something any machine can do, so the best thing I can suggest is to see if you can actually get you're recording system to output the video is a slightly smaller and usable format, like an .mp4 for instance, before you go down the route of conversion.
Hope that helps