Shrine vs. Carrierwave

I noticed in the screencasts that the first one is on Carrierwave , but later on they're on all Shrine.
I really like https://github.com/diogob/carrierwave-postgresql (not sure if it supports Shrine) hence I go for Carrierwave.

What am I missing?

It all boils down to personal preference. If you are comfortable using Carrierwave, continue using that.