At 1:58, the moving clock is slower so (2L/C) needs to be multiplied by gamma so that time is longer. Dividing by gamma would make the moving clock tick at a faster rate. Gamma is always greater than 1.

This works for me. It’s helpful to get used to using formulae in different situations before seeing the derivation later in order to cement the understanding before getting bogged down in those details. Thank you for providing this course – your teaching method and style are excellent and you put across concepts in a way that are easy to grasp.