I posted earlier that running was the option I would most likely employ, and I still believe that. I once practiced with knives for a pretty decent period of time and came to the realization that unless one person is incompetent, even the "winner" is likely to bleed out before help arrives. So, even though I still say that an unarmed person (like the victim in the video) should run as their first option, if that option is unavailable to you then you are going to have to decide that you want to live, and nothing else matters.
As far as the video goes, I think it's unlikely you can score a solid hit on the incoming knife arm; it's almost as unlikely that you'll be able to grab it. Rotate the wrists out so the brachial artery isn't exposed, and get inside the strike so the blade hits the outside of the forearm, upper arm or shoulder. Try to clinch with a bear hug that traps his arms to his side above the elbows. Hit him with your incoming head if you can, they bury your teeth in his throat and tear until he stops moving. The carotid is buried about 1 1/2" deep. If you can work your way to it, it can stop the attack in about 8 seconds.
I've never been in a real knife fight, and I hope I never am. I don't know what would work, but if I can't run I'm going to do whatever it takes.
Running may not be an option.
Your exit could be blocked.
You could have loved ones that would be attacked.