I said the attacks in the video I posted were more realistic. They still telegraph and Uke is way too compliant in my opinion BUT I do believe they are headed in the right directions throwing hooks, haymakers, more straights to the face, etc. All technique aside, I think they are a good example of how many, if considering self-defense, should be changing some of their training methods.
As far as knife defense, I consider it to be completely theoretical. I don't believe in 'catching the arm'. wielding the knife. In my own training, even with no adrenaline altering my motor skills, I get cut almost every time and many times, in a deadly spot. Imagine someone wields a shiny knife with and you can see the intention in their eyes. I don't think you're gonna get a kotegaeshi as easy as you think. It's more than likely going to turn into a scrappy blood fest. Here, like someone else mentioned, atemi is more than likely necessary.
Great video on this subject. http://www.youtube.com/watch?v=E61jnJe_1SI