2 Mistakes at 2:50 and at 3:46

at 2:50: we should multiply the first row of X with the first column of W to obtain Y1 and the first row of X with the second column of W to obtain Y2 contrary as shown in the video!
at 3:46: the bias should be of size N*M because it is always in the same size as the output and it is added to the multiplication output of X*W which is also in the size of N*M