There are a number of ways to save your movies as very small files -- but I wouldn't consider them storage!
Remember, once you've compressed and reduced the quality of a movie to make it very small, you'll never be able to restore it again to its original quality.
I'd recommend you just save your videos in DVD format on a DVDs. That way they can be viewed by almost every and easily recovered in standard definition, if you need to re-use the video in a future project.
I dont think i was clear. I will keep the originals (in best quality) but just want to make the interviews available to people to see and as i will be distributing quite a few copies i want to try to fit all the interviews on one dvd (there will be about 20 hours of interviews), and i am wondering what format i might use that people can still view the contents of the DVD in say 10 years time, on either a PC, or Mac.
Is that clearer now?
Even with DVD-9's (DL), 20 hours of interviews, at the lowest possible Bit-Rate, will still result in a multi-disc set. I would anticipate, at a very low Bit-Rate (you should not have much motion), you could squeeze 5 hours per DVD-9. Now, I do not know what PrE's lowest quality limit is, so you might have to do the authoring in another program. Steve, or another subscriber, might want to comment on Sony's DVD Architect, as it might allow for a lower quality (Bit-Rate), than PrE.
I dont' think anyone can predict what format will stand the test of time, sound space. 20 years ago, you'd have thought 5" floppy discs and Zip drives were the way to go -- and you see how that worked out.
But if you just want a low-quality, small file that people can view and you want to fit a lot on a disc, just use the Share/Portable Device/iPod output format.