How does Netflix recommend movies? Matrix Factorization

Announcement: New Book by Luis Serrano! Grokking Machine Learning. bit.ly/grokkingML
40% discount code: serranoyt

A friendly introduction to recommender systems with matrix factorization and how it's used to recommend movies in Netflix.
Accompanying Notebook by Yannet Interian: https://github.com/yanneta/pyt....orch-tutorials/blob/

Gradient descent video mentioned at the end: https://www.youtube.com/watch?v=BR9h47Jtqyw

What is Machine Learning: (0:05)
How do recommendations work - Netflix example (0:40)
How to figure out dependencies - Matrix Factorization (7:35)
Matrix Factorization Benefits 20:38 How to find the right factorization (16:03)
Error Function for factorization (26:35)
How to use the factors to predict ratings - Inference (30:14)

(Thanks for the timings, Samarth Piano Posts!)