Meatyard is a favorite of mine. One thing that to learn from him is the idea of having 5 or 6 long term projects to work on. When he ran out of creative energy in one project...he would work on one of the others.
I have to say the motion-sound work isn't as interesting to me as some of his other work; I love his kids in the abandoned structures, but that first motion sound certainly achieves what he seemed set out to do. You can almost hear the buzz cicadas in that image. The second one you post isn't quite as successful... maybe that big tree trunk is to heavy a presence in the image. To me at least.
Another portfolio that is a departure from what he is known for, Zen Twigs, are delicate studies of branches and water. Really interesting, and I think this more contemplative work the Zen Twigs and the Motion Sound probably informed his other work profoundly, if not very obviously.
I'm a fan... thanks for resurrecting this forum!