> Anything not already processed at the time of
> interruption has been lost from the cache
> and will always be redownloaded.

But non-redirected files that were downloaded hours or days later are not
redownloaded.  This only (and always) happens with these same files.

> Dynamic content (content created on the fly)
> always has a newer timestamp
> and is always redownloaded.

But this content is static (mp3, mp4, etc).

One place where this seems to happen is
<http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-013-electromagnetics-and-applications-fall-2005/textbook-with-video-demonstrations/>
(a course I'ld like to follow when I am in Africa and not on the Internet)

Thanks for looking into this!

Biep