From what I've seen, another great tactic is the arm sweep (think wax-on wax-off, Daniel-san). Moves the aiming point away from your body (good) and if you're good, you can then get a hold of the arm with the firearm and keep it from being pointed at you (very good).

Not that I plan on being in any situations where I might need this capability.

Will watch the video later to see if what I'm talking about is in there.

It's like they say: Run from a knife, charge a gun.

That's the problem I've always had with kung-fu movies. Sure, the moves are cool and all, but if a mo-fo comes running towards you looking to get all Bruce Lee on your ass, and you have a gun, for chrissake PULL THE FUCKING TRIGGER already!

The problem is reaction time, distance, value of the target when alive, and timing your charge right (assumes the firearm user can aim well and has the huevos to squeeze the trigger.

Reaction time: Because they've got to see you move, determine that the move is detrimental to them, and then react it gives the defender an advantage.

Distance: If they get close, it's somewhat easy to knock the barrel aside before they can pull the trigger. If further away, you still may be able to get away with it by charging in an elusive manner.

Value-alive: If you're more valuable alive than dead (especially alive without leaking fluids), then they've got to factor that in, further delaying the reaction.

Timing: If you can time your charge with them being distracted, blinking, or what have you, now you've got momentum plus the others above working for you.

So, key points here - if you're going to use a firearm to hold someone hostage (legally, of course) make sure to do the following:
-Get them on their knees, but with a straight line from their knees through their hips to their shoulders and have them lean forward a bit. From this position, they've got no ability to launch anywhere. In order for them to make any move to flee or attack, they've got to either fall forward or lean back, both of which are visual clues that give you more time to stop the action (verbally) or prepare to defend yourself.
-Make them intertwine their fingers in their hair and at the back of their head. Same principle as above.
-Don't get too far, but not too close, either. That way they can't get to you without several physical moves but they're still an easy target.
-Make sure they know they aren't about to die. If they know they'll live to fight another day, they're much more likely to not try and fight. Don't let the pendulum swing too far the other way, though - they need to know that you will take action if they don't stay in that pose.
-Get the police there quickly. This isn't a long-term situation. Don't make it one. Just make sure that the police know you've got the firearm so they don't get all DC-cop and shoot you.

**This isn't legal advice. Make your own damn plan. Don't sue me.**

ehh

Make them lay down on thier stomach and reach back and grab thier ankles.

That means in order to do anything they have to let go of ankles get hands underneath them and leverage up.