Sarah Verney was traveling near Kokadjo, in northern Maine, when the car had to slow down because there were two lynx in the road. Lynx usually do whatever they can to avoid humans, so it seemed odd that they didn't get out of the road. It turns out these cats had very important business with each other. They stopped traffic while they had a bit of an argument.
Verney wanted to record what they sounded like, so she rolled down the window. The terrifying wildcat screams we expect turned out to resemble two old women arguing. Redditor stanfan114 nailed it.
They sounds like the old ladies from Monty Python with the penguin on top of the television set.