There is nothing that compares to watching middle-aged men talking nerdy to an invisible audience and scribbling math on a chalkboard! I collected a list of free lectures which i enjoyed. The collection has a focus on STEM, and includes math, probability, information theory and electronics. I will probably add lectures to the collection when i stumble on further good ones, but in the meantime, i hope you enjoy them, too!
Linear Algebra by Gilbert Strang / MIT
Electronics by Digilent Inc.
Information Theory and Pattern Recognition by David MayKay, Cambridge
Statistic 110 by Joe Blitzstein, Harvard
Single Loop Control Methods by Kevin Starr, ABB