What is the best video format for 50+ year movie storage?

Question

Objective:  In what video format should I store my family movies on an external drive?  I want these family movies to be viewable by future generations in 50 - 70 years, so what video format / type is recommended?
Background:  I have an iMac, OS X 10.7.5.  I use IMovie '11, version 9.0.8.  My iMac has an internal DVD player and burner and iDVD is installed.
I have dozens of family movies (total 80+ hours) dating back nearly 70 years.  All these films have been digitized and I have imported many of them into iMove as events, then I edit them with title pages, transitions, music, etc.  When a "project" is completed (Between 1.5 - 2.0 hours or less) I share the project to iDVD where I burn it to a DVD.  Within iMovie I save each of these projects (on the internal Mac HD, which consumes very little space) and on an external drive I save for each project:
- a disc image (DVD.img) whose size is about 4.5 GB
- a copy of the iMovie project, whose size is about 60 MB (the original project is in iMovie, in the Mac internal drive)
- the original digitized raw movies imported into iMovie as events and are formatted as .mov (these are large size at 8 GB - 20 GB each)
- the finalized and fully edited iDVD which is formatted as DVD.dvdproj (these are very large size at 20 - 24 GB each)
As you can see with all these disc images, projects, events and DVD projects stored on my external drive I am at nearly 1 TB of storage, on my way to 1.75 before I comple editing all movies.
While I manage pretty well the editing my movies within iMovie, and how to create an iDVD project and then burn a DVD, I have no understanding of the technical aspects of the multitude of different movie formats in the market nor of Quick Time and its format.
I am told that DVDs will only last 10 - 15 years and then begin to deteriorate.  And iMovie '11 won't be arond 50 years from now.  Nor will the current / recent versions of iDVD.  Thus, for posterity:
1.  In what format should I store my family movies on an external drive so they can be viewed by family members 50 - 70 years from now? (best chance for viewing, since we don't know what formats they will have then)
2.  How do I convert from what I have (disc image, iMovie project, DVD project) to your recommended format?
Thank you,
HDP

Answer 1

There is no such format for movies or even Photographs. Frankly we can't guarantee the persistence of any format past the next 10 years, not to mind 50 - 70.
Codecs are being improved and created all the time, and this process will continue. In 50 years time we may still have .mov and .avi files, but the codecs that create the movies within will have changed.
One thing is reasonably sure: DVD will be as deader than floppy disks are now. Ditto Blue Ray. They're on the way out now, and in 10 years they'll be curiosities.
So, what's the solution:
Best I can suggest is to keep your movies on volatile media like Hard Disks (with back ups on other disks, or course). Progress will be evolutionary - as new formats come along there will be the option to migrate older data to these newer formats, and that's the trick. As always, when it comes to migration, the more data available the better the likely result, so keeping your movies in the least compressed versions possible seems a good approach.
That and a dollar will get you a cup of coffee someplaces, but nowhere fashionable.
Regards
TD