That's funny!

The video said they were guessing the coolness of the cooler felt good to him. I'd imagine he walked in there possibly because humans went in there at the hottest part of the day (aka noon, lunchtime!) and might've thought, "Well, it must be cool in there." so he walked in, then felt the cool-air from the cooler and hopped in to escape the heat of the summer. Then as they dragged him out, he probably was seemingly mad because he might've been thinking, "Hey, can't a coyote cool down for cryin' out loud?!" or something like that.

Even though, I was just guessing, but he could've.