I agree with the above too, I only use it to emphasise a point during a ki development lesson. I don't see it as aikido either, it is a bit of a trick, but does require complete co-ordination coupled with good timing, so as a training exercise it has its uses. There are many other ways of dealing with that particular attack.
The timing aspect is the main reason I prefer to see these kind of tricks demonstrated starting from a static position. One less variable to obfuscate things.