Yep, just remember those old Nikkors with the aperture rings? Those are PERFECT for video needs. Those old AIS gems are starting to creep up in price again believe it or not. Never had a FM2n but the F3HP is my favorite film camera of all time. It's a TANK. No raining here sir, any time we wanna reminisce about the glory days of film (aka about 4 lousy years ago) pile it on.
BTW, I did take a quick look into the F3HP while shopping for my kid's photog class. Seems nice, but looks like there are actually some things more desirable in the FM2n, if certain auto features are not needed. The used market for film cameras does seem kinda odd now(?) because of the niche that remains leftover, eg. photog class students, DSLR videographers (for manual lenses), etc. Your much loved F3HP doesn't seem to fetch any more than the FM2n -- it probably even fetches less at times depending on which actual FM2n (as there's one w/ the old Titanium honeycomb-patterned shutter blades and the newer, more common one w/ Aluminum blades as well as some special limited/collector's edition titanium-bodied one that probably still fetches serious $$$).