Having used a similar design on our robot last year, I would reccomend using
"Acme" threaded rod if you stay with this design. We has issues with the threads getting munched in high load situations, and acme threading makes this much less likely. The threads are trapezoid shaped and show much better wear characteristics when we used them.
Word of warning though, this will be a more expensive solution than what was shown in that video. Acme nuts and rods won't come cheap but you can probably get a reasonable deal if you shop around.