Looks like they have 3 layers, your background layer, then your letter blocked layers which alternate back and fourth, I suggest you take the two tracks you want to switch from and put one on top of the other and use your blade tool on the top layer and cut out every couple fames and delete them leaving spaces in between that way when you play back it will have that effect.
Your going to have to do it manually with the blade tool
-Greg Baldi
Post Production Editor