Hi, here I made a video that explains the Index skew and how the delta hedging of it creates regular patterns in the price of the SP500:
Many Vol funds are aware of these dynamics and have their own unique strategies that go around to capture some of the alpha that these market imbalances produces.
This video was made in collaboration with Cem Karsan; those of you who follow his Twitter feed will be well aware of how he talks a lot about "Gary" and "Vanna".
Some of the dynamics he talks about are captured in this video.
RV also did an interview with him here:



This video assumes you are already aware of how market makers delta hedge gamma, vanna and charm exposures. If you are not already familiar with these, 

You can learn about delta hedging of gamma exposures here:

And if you don't know how vanna and charm exposures are delta hedged, you can watch this: