Having been a teaching assistant for intro programming classes targeted at non-CS majors, I disagree. You don't need to understand what a 'stack' or 'heap' is to understand what's going on and for this to be useful.

And even if it's too complicated to be useful for people on their own, being able to use something like this as a teaching aid would be very helpful. The number of people who have trouble grasping even what most of us consider very basic concepts like iteration over a list is astonishing. Trying to explain something you find trivially easy to someone who doesn't understand it at all is an exercise in frustration for both people. I usually resorted to doing a manual step-through on a whiteboard or piece of paper, but this is much nicer.

I would discourage people from using this constantly, just because I think having a step-through debugger handy constantly will prevent you from developing necessary debugging skills. (The concept of wrapping something in print statements is another thing I take for granted that's not obvious to some people.) But I still don't see how something like this could be anything but a net positive.