Quote Originally Posted by Brother Oni View Post
As Rhynn said, any knife defence techniques are going to be taught in optimal conditions for well telegraphed attacks. In an ideal situation, the officers watching the training video would then have practical knife defence lessons to follow up their classroom tuition.

From my own training, any open handed knife defence techniques are strictly a last resort - running and/or talking to defuse the situation takes priority.

For untrained attackers, telegraphing is actually quite common; with trained attacks intend on hurting you, the only real defence that works is a double tap, centre of mass.
I feel that even if verbal commands also don't stop the assailant, anything that buys time to draw your weapon is worthwhile. In the UK, shouting out "Stop! Armed police officer!" often makes people think twice, or at least buys valuable moments for the officer to draw his weapon.

As a final thing, I'm not sure how common it is in the US, but UK police officers these days typically patrol with body armour (stab proof vests primarily) so it gives them a bit of defence.
That's the general idea of the video, yes. If someone believes this stuff without having those caveats you mention... they will unfortunately be destroyed.

Quote Originally Posted by Rhynn View Post
And in many real situations with such an attacker, you'll never have a chance to. You won't know it's an attack until the guy walking past you is suddenly stabbing you.

Knowing how to defend yourself is always better than not knowing, but the sad truth is, knife attacks are very, very hard to defend against for many, many reasons, a big one being surprise. Knives are very concealable; I remember a buddy of mine hiding a kitchen knife with his bare arm and giving everyone a nice surprise by suddenly screaming and stabbing it into the table we were sitting at... Smaller knives are still quite deadly. Your standard prison-yard-style shanking is pretty hard to defend against, if you don't know to expect it right then.
Anyone who knows how to use a knife will be very good at surprise attack. Keeping alert of possible danger is the most important line of defence, since it allows you to evade dangerous encounters all together at times, and you're helpless regardless of your skill if you're killed before you realize there's danger.

As for concealing the kitchen knife, here's a funny example: http://www.youtube.com/watch?v=hfBRbKyzUCE
Not sure if he could actually walk with those.

Prison-yard shankings are difficult to defend against even if fully prepared and armed with a sword. The sword brings it from near impossible to quite feasible, at least.