I will add that watching this does not appear to be the most useful for judging market bottoms. Often times this founds bottom and bounces the exact same day as equities. So, for that aspect at least, other indicators may be of more use, such as VIX/VVIX.
This just can give some advanced warning before the market tops that the big money is starting to pull back from risk, just adding yet another warning sign to look out for prior to large corrections.