12:06 (talking about the 5th diagonal and the relevant numbers) - You substract the first number from the second number (5-1) and substract the difference (4) from the difference of the next two numbers (35-15), which is (20). You get the difference of (20-4), which is 16 - the square of (4).
7:04 These equations for Pascal’s Triangle can also be used to estimate the area and shape of a 4D hyper-pyramid. The equation would probably be something like this: (n(n+1)(n+2)(n+3))/20