My experience says magnetic tape has rather a longer life than home burned
DVDs, etc. I reckon you're lucky if they last 10 years without developing
errors.
Quite a problem, archiving. So far properly stored film seems to have the
longest life.
Magnetic tape, stored in a good environment, does have good lifespan.
Even so, a lot of tapes are probably several years old at this point
so the remaining alternative is duping back to tape again, or another
method. We can't really know if today's DVDs will last 10 years or
not, since they've not been around 10 years and accelerated testing
tends to use perfect samples and suggests far longer. I would tend to
trust data on a slow burnt DVD more than a CDR since they are encased
on both sides, providing they're not set in strong sunlight a long
time. Either way, a good strategy would be to make two copies, each
on different lot, different brand of media.
Another option these days might be flash storage. Considering the low
resolution of VHS, videos with typical compression shouldn't be very
large, so $1/GB flash prices we're starting to see these days could
allow for reliable storage at reasonable cost (if it's worth backing
up at all, anything that can't be had on a retail DVD). In 10 years
when the flash storage retention rating has expired, flash memory will
be that much cheaper per GB.
