at 6:26 i can't make the 45 angle to move the loop downward ...and even if i do the g+z key it goes 1 side only.. .Please let me know how to do it.
It doesn't have to be a, exactly 45°, angle..
G, Z will move your selection on the Z-axis; if it only moves 'one side', that means you didn't have the entire loop selected (anymore...)