All JWs need to watch this great documentary...it may give them pause for thought.
One film that helped me was a BBC piece on the Exclusive Brethren. The similarities were so striking that I stopped watching it a couple of times worried that I was being "tricked into watching an apostate video" even though it was not about Witnesses at all! It also helped someone else I knew leave. If you have ever read the second or third (can't remember now) Steve Hassan books he talks about how building trust and not putting down the loved ones cult is important but that introducing information on other groups can be very effective psychologically in freeing a loved one from a cult. I know it is easy to get discouraged and think that no one is going to change or wake-up......but we all did......so it's still possible. And getting someone engaged in seeing how egregious the actions of another cult are (with the possibility of them somehow identifying with it) can be effective, I speak from experience
It's a tricky one. I do understand as some have already said that showing JWs films about other cults could make them feel better about their own group.
I think kjg123 made an important point. Showing them films about other cults that are very close to their own is probably more effective because, although we can see the similarities between scientology, JWs, FLDS, etc etc each of those groups view the other the same way: they are damned, we are saved because we have the truth - which is another similarity that they (all cults) fail to readily recognise.
People in cults are great at spotting other cults...oh the irony.