I watched that video tutorial, thanks for posting it.
I do my cutting with the ruler really differently than she does! I have my fabric folded in half twice, because my mat is only 18x24, but I overlap the 0 on my mat a little bit, line my clear ruler up with that 0 and cut there to get my fabric even. Then I look for say the 5 on my cutting mat, line my ruler up with that 5 and then cut to the right of the ruler, where it looked like she was using the 5 on the clear ruler to see where to cut. But I'm also sliding my ruler from right to left, instead of left to right like she was doing.