Is ar7200 bgt-only or is it found on IWD/PST too?
BGT only.
Those other movies are
ok... if someone hasn't deleted or overwritten their movie biffs, which is perfectly possible to do and still have a functional game, unlike other types of resources like areas.
I suppose another argument against using movies is that they're some of the biggest game resources you can load.
I use the following:
tutu = fw0125.are
bgt = ar7200.are
bg2 = ar0083.are
tob = ar6111.are
iwd2 = ar6050.are
pst = ar0104a.are
bg1 = ar0125.are
tosc = ar2003.are (& not iwd1)
iwd1 = ar2116.are
how = ar9109.are
tolm = ar9715.are
ttsc = fw2003.are
ca (classic adventures) = tc1300.are
Those are all platform-unique AFAICT with the exception of totsc which unfortunately doesn't seem to have any uniquely-named areas that aren't in some other game. BG2 still needs the "not" checks to make sure it's not Tutu, BGT etc.
Now someone might say, "but someone could copy areas from one game to another." Sure, if they're stupid enough to do that without using a unique prefix. They could also do that with movies, and copying areas is a lot tougher because of all the related resources.