I have looked long and hard for you friend...but i am fruitless from my journey
i have found a few things that may be able to assist you, just search in google for:
ace codecs pack (can be dodgy)
or microsoft direct show (no longer supported either, but it will fix the problem if you can find it)
or finaly check out these patches which allow the use of other codec to render the streams
http://rpghaven.uni.cc/goldfinger/ff7/ff7betap1.exe (movie patch)
http://rpghaven.uni.cc/goldfinger/ff7/ff7102zx.zip, (1.02 patch)
And the chocobo patch in case it freezes when racing in the gold saucer
http://rpghaven.uni.cc/goldfinger/ff7/ff7_chocobo_patch.zip
I cannot guarentee at all this will solve your problem as i do not own a pc version of ffvii but try it out!
Also as kie said about the disc being faulty it is a possibility....
Also if you have a pirated version (shame on you if you do) it is well know it is a terrible iso and is full of corrupt data
well i hope this may help