Video title is How Maxwell's Equations Were Discovered, HN's regex thingy changed it to Maxwell's Equations Were Discovered. (My brain's regex changed it back :)
The original title is much better How Maxwell's Equations Were Discovered. As it is now Maxwell's Equations Were Discovered it sounds like they were just discovered or someone rediscovered the equations.
https://www.youtube.com/watch?v=sDlZ-aY9GN4
which explains that magnetism is just an emergent property when you start from Coulomb's law and relativity.