For FF7, install Fidecula's cetra patch. It will force the movies to run in 32-bit color mode which will be much better.
Also you can enhance the fmvs by using virtualdub
Or replace the old fmvs with the newer clips from ac,cc and doc
There are many remakes of the old fmvs which can be found in advent children and crisis core:
- FF7 Opening
- Aeris's funeral
- Sephiroth surrounded by fire
- Jenova taken out from the reactor in Mount Nibel
- Meteor seen from space
- The Mako Gun gathers energy and shoots
- Rufus being shot by Diamond Weapon
If you have Advent Children in HD then in 320x224 resolution of ff7 movies they will still kick ass