Cool video.
Depends on species of course, don't think you'll see many schools of adult northern pike or muskie.
Agree with this, including what I've seen in wild video in my own tanks where I've kept groups of severums or other species most people don't keep in groups, and in other tanks, where I've seen adult A. rivulatus groups (gold seam, made for a beautiful tank), adult oscar groups, etc., just takes a large enough tank, in some cases a large enough group, to bring out the social behavior.Loose shoals are quite normal in nature, and I agree with Celebrist, the antisocial way oscars and many cichlids act in most aquariums, is what's out of the ordinary.
Depends on species of course, don't think you'll see many schools of adult northern pike or muskie.