I shot a nice little video of a combine harvester here in Oxfordshire about a week ago, first time I had used the 1080P @ 120fps and....it came out in slo-mo! Oh well, a bit of tweaking and I got it back up to speed.
Chaff dust most likely. Combines spew out the waste in the rear like that.Drought there also? Looks like tons of top soil blowing away.