All have official releases, not too hard to find.
Nick Fury-
I think this was only broadcast on TV for one night. I'd love to see it.
Generation X-
I have a crappy bootleg of the original broadcast, but it was released on VHS in Britain with extended scenes that were edited for TV. I'd love to see it.
M.A.N.T.I.S.-
My holy grail! Does anyone have this?
Spidey-
As I said, I can do a VHS to DVD for the original. Laserdisc would be best if someone has one. Also, if you're in a PAL nation, I assume your VHS copies would make for a much better DVD than my NTSC.