PRO TIP Block youtube.com at the DNS level — Pi-hole, NextDNS or your hosts file — but allow youtube-nocookie.com and i.ytimg.com. These tutorials keep playing; the rabbit hole does not.

38: Time dilation and length contraction – Part 2

3K views on YouTube

NTNU Lectures 51 tutorials here

Physics

Jacob Linder: 14.03.2012, Classical Mechanics (TFY4345), v2012 NTNU

A full textbook covering the material in the lectures in detail can be downloaded for free here:
http://bookboon.com/en/introduction-to-lagrangian-hamiltonian-mechanics-ebook