Looks like they're cleaning the front porch. I've seen my girls do that and they're typically using their tongues in the process. Maybe licking up pollen dust or something?View My Video
I visited an old vacant house where I am going to remove a massive hive about sundown. Outside the main hive entrance, rows of bees were moving foreward a few steps, and then backwards a few steps. They were NOT flapping their wings, so it would not seem to circulate air to cool the hive. Their heads were down the whole time. Has anyone seen this behavior?