These clips were taken on Sept. 8, 2012.
September is the primary month in which buck White-tailed Deer rub the velvet from their antlers in preparation for the rut (although there is variation in this date, and velvet may be rubbed off as early as late August, or as late as November). The triggers for this rubbing behavior are the result of a battery of hormones, but changes in testoterone levels (often triggered by changes in daylength) are important. For example, according to Miller et al. (2003) the "hardening of the antler and shedding of velvet are a direct result of rising testosterone levels cued by shortening daylength."
Compare this to the first hint of antlers since this year, way back in April.....
Miller, K.V., L.I. Muller, S. Demarais. 2003. White-tailed Deer (Odocoileus virginianus). In Feldhamer, et al. Wild Mammals of North America: biology, management, and conservation (second edition). Johns Hopkins University Press.