[tongzilla]

Accumulators are the angles. It's pretty easy to see on video.

Clubhead Lag is the Pressure you feel in your Right Forefinger. Clubhead Lag pressure is what stresses the shaft.
It's harder to see on video because you can't just draw lines to show it, although it is obvious when you have major Clubhead Throwaway (which gives a Bent Left Wrist). And ideally, you should feel this Lag Pressure from Start Down to basically the Finish.