In one of the videos Andrew distributes the matrix multiplication with respect to the sum:
A ( C + B) = AC + AB
This makes sense to some extent because in the end the elements a(b+c) = ab + ac . I checked out a few Cheat-sheets but didn’t really find any useful and good-looking chart.
Is there any summary of matrix properties including the former one that you find useful and maybe would link to ?
It’s commutativity in Math. I think it is better to find a good reference for Linear Algebra.
One example is this.. It is not a cheatsheet, but covers quite well.
That is certainly not commutativity. It is distribution with respect to the sum. Commutativity is not generally true in matrices and it is this:
AB =! BA
There are cases where is valid though, I think with the identity and some other special cases.
Right, it’s not.
What I wanted to say is, find linear algebra . And, you also need this, which I’m always referring. 
Thanks for the resources.
actually just doing the operations makes it obvious,
Yes, if you look at one element of the resultant matrix and consider the operations that happen at that point, it is clear that multiplication is distributive over addition for matrices, just as it is for scalars.