Tesla AI Day 2021 Model - Feature Queues

I have been trying to understand how Tesla's model works (as presented by Andrej Karpathy [here](https://www.youtube.com/watch?v=j0z4FweCy4M#t=64m54s)). I am unclear on how they are caching the features. The overall architecture only seems to have camera image inputs at a given timestamp, and they say they are caching features from previous timestamps.

I understand that the cached features will be passed into an RNN in the format something like BxWxHxCxT. But how does the back-propagation work through the cached features in order …

ai day computervision feature tesla