caped crusader
Brown Belt
have you ever yourself been in a real situation against a knife?Most of that was actually covered in the video.
As for the last point, it's unlikely an attacker is holding as hard as he can at most times (perhaps during an actual stab, especially if they have training/experience), simply because it's an unnatural way to hold. If they are at distance like this, they probably aren't gripping as tight as he was.