I like the way you think, and clearly you do have a lot of martial arts experience. Very smooth.
I noticed that you didn't fight the strength of his arm/body, and just let the weapon glide on by. I see the good in this, but I also see the bad.
I always try and let the bad guy's body do what it wants to do, instead of trying to make his body do something unnatural. However you are violating one of the basic principles of weapons takeaways, by letting the blade pass through your center of mass.
If instead of a box cutter the suspect was holding a butcher knife in the ice pick grip, a base ball bat, or a sword, you would have quite possibly gotten cut or hit, buy letting the weapon pass through your center of mass.
Why not try something like the SPEAR System? This is a quick, almost reflexive response, that would work against all of those weapons, and wouldn't require the weapon to pass through your center of mass(which as you know, contains all of your vital organs).
I understand that there is a time to let the weapon pass by, but I think that you are at too close of a range for this technique to be effective every time. In other words, I like parries, but I think that at the range you are at, a block would be much more appropriate.
Don't get me wrong, I think the technique could work. You do make it look easy, but I certainly wouldn't recommend it for somebody who doesn't train all of the time.
Don't be offended. I like reading your posts. We also have so much more in common that we have differences. Just my thoughts on it.