You can do what you've asked in Mac OS, or using some special software depending on the choices you make.
If you compress your movie to make a video DVD, you have reduced the quality substantially in exchange for a file that is 8-10X smaller so it will fit on the DVD. You can "rip" the DVD later using a program called DVDxDV to get back to an .mov file but you will have lost some of the quality. Some people use a piece of freeware called MPEG Streamclip, but I have seen audio drift in some longer clips using this program. Your mileage may vary.
You can write your footage to DVD without any additional compression but it will take up a lot more room so this will likely require several DVDs depending on the amount of footage. This is called a DVD-ROM and is essentially like a very large CD. MacOS X supports this type of burn from Finder. look in MacOS X Help for specific instructions.
Hope this helps