I've never seen the video, but I think I build my strings the same way. Happens to me sometimes, too.
The twisting that you do on the loops doesn't doesn't impact the amount of back twisting, because you're twisting toward the end of the string. The amount of back twist is determined by how long the section is that is weaved back into the main string to make the loop, the longer the tag end, the more the back twisting on the main bundles. Depending on the string maker, this can be from four to seven inches. Mine are usually about 5 inches, and I backtwist the main string bundles 12 full revolutions, sometimes a little more. That may or may not work for you.