Massive blackbird flocks

While spending some time in Lancaster over Thanksgiving, I was able to get out and drive the farm fields looking for birds. One interesting bird phenomenon of the region is the large flocks of blackbirds that roam the fields during winter, presumably attracted by all the grain remaining in the fields after everything is harvested.
The flocks usually consist of large numbers of Red-winged Blackbirds and Common Grackles. Mixed in the flock in smaller numbers are Brown-headed Cowbirds and European Starlings. With a blackbird congregation this large, it is sometimes possible to pick out a Yellow-headed Blackbird or Brewer’s Blackbird in the flock. No such luck yesterday though. I took a couple videos to give you an idea what the flocks are like.

So what do you do when you see a huge flock? Any tips on counting/estimating techniques? Please leave comments on the post with your counting tips!