Caching implies short term use. Yes, all of the things he mentioned could be useful for short term caching.

We both know that modern social tech is built on big data crunching, meta data analysis, and using "micro-pyschology" (adding up all the small habits) to influence people.

Do you use a search engine? Do your friends use Social media? Have you been photographed in the last 3 years and stored on a google/facebook server? As much as you want to believe "your data" is not a part of this dataset, you are absolutely a node on this graph.

My fav eye-opener: Facebook tells you about your friend's photos that you could be tagged in. Most people forget that facebook could also tell you about the strangers photos you are in, but it would freak you out.

I agree that much of what he's showing does not need to be kept by Facebook or Google or whoever else and I've argued for strongly incentivizing companies to keep as little data as possible elsewhere. I just feel like he's presenting his material in a highly sensationalized manner with the express goal of stoking as much fear and outrage as possible among a less technically-inclined audience.

I suspect that restricting facial recognition in Facebook photos to friends of the photographer increases accuracy by a lot.