From that YouTube page, Jonna Jinton writes:
"In the middle of the bright summernight I went out to call for the cows. I thought that maybe, something deep inside them, remember the sounds from the ancient times when people called for them over far distances.
They came running, together with a million mosquitos 
But what a magical night."
So clearly, the mosquitos favor the dress, in case calling those is part of the goal.
If the cows are out past the fence, it works too:
This one has a really great ring to it:
