Those are great animation tutorials.

A little while ago Ockham posted an explanation of why using IK within an animation causes the jitters.

As I understood it his advice was to use IK for preparing keyframe poses, but not during the animation sequence itself.

It might be worth doing a search for "ockham" and "IK" to find that thread... it was quite recent, I think.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)