When I find my rhythm is off or otherwise need to work on my lower body I often practice throwing standstill with putters and mid ranges. I work on throwing with only 75% or so arm/upper body speed and getting distance out of my weight shift and push from the back leg instead of my upper body motion. I find that it's a lot easier to really get a feel for your lower body that way.
Once I get comfortable doing that with consistent results I'll speed up my arm for a couple rounds of throws and then eventually work back into the full run-up.
In a way it's similar to the method Dan Beato is teaching in that video. It tends to work pretty well because it's a lot easier to make changes at 75% speed with less moving parts than it is at full speed. As an added bonus, it's good practice for standstill touch shots because it's basically the same form.
Practicing in a similar fashion might help you bridge the gap to the new technique in you lower body. I find that in both ball and disc golf it's a lot easier to take baby steps like this than jumping in and trying to get the whole motion right immediately.
"Ask not what your disc golf community can do for you, but what you can do for your disc golf community." - JFK (Kinda)