hdd's are not sealed, the have air filters to exclude debris.
http://www.pcguide.com/ref/hdd/op/packAir-c.html

iPods and other media players with hdd's have operating limits.
Doesn't mean they won't work above their rating, but it's risky and may
depend somewhat on the latitude.

My DV recorder also will take SD cards and tapes and has AVI inputs,
but I like the fly and forget method described above. The AV-500 now
comes with 100GB drive.

Frank