You should check this thread.
I believe he is the actual builder of the vid you linked. He uses the shorter 5" filters. Upon stumbling on that thread, I built one(using the regular 2"x10" housings) and absolutely love it. In these reactors, you can use a regular pleated sediment filter. Don't use the ones designed to take other things out of your water, don't really see it being an issue but I never personally tried it. Some of the purigen gets lodged in the filter and the rest gets blown around.