Interestingly, the program doesn't mention two of the largest groups that come to mind: JWs and Scientology.
I noticed that as well - seemed to feature Mom and Pop cults - I think Hassan estimated some 10000 of these in America alone.
I suppose that JW's, Mormons and Scientologists go to church but are otherwise functional members of society to a greater or lesser extent.
As opposed to these Grade A cults featured where the members are physically separated from society, which make better televison than a bunch of smarmy Bethel PR droids claiming to be just regular guys.
What the program clarified for me was how the combination of youthful emotion, vulnerability, idealism and reverence for 'spirituality' make college age people so fertile for recruitment. That was certainly the case for my convert parents.