The problem was that I was shooting through a window and a screen, and if I dared to open either I would be sure to scare it off. Beggars can't be choosers, right? Watch it below and observe the behavior as it quivers it feet, stomping one or the other on the ground while foraging for insects.
This intricate little dance was very funny to watch up close. However, it had scientific value as well. The Hermit Thrush account on the Cornell Lab of Ornithology's All About Birds site has this to say about it:
"Hermit Thrushes sometimes forage by “foot quivering,” where they shake bits of grass with their feet to get insects. They also typically begin to quiver their feet as they relax after seeing a flying predator. Some scientists think the quivering happens as the bird responds to conflicting impulses to resume foraging or continue taking cover."
That first line is exactly what you see in the video, and as you may also have noted, it was very effective as the bird captured several prey items while I watched it. What I can say for certain is at no time was it under threat from an aerial or terrestrial attacker. There were other songbirds around that were not agitated in the slightest. This behavior was maintained the entire time I watched (several minutes), first from a distance, then up close. I was so close that it would not have stayed there had it seen me, so I was not affecting it. I think it was nothing more than a crafty foraging behavior it utilized with great success.