So I grabbed the camera and recorded a quick video of the sounds. You can't see anything in the video except the neighbor's back yard, but you can hear the sound quite clearly. It was echoing through the entire neighborhood so it was hard to ignore. It even had the local wildlife a bit upset; you can hear the sounds of the birds and several dogs going crazy in the background. Around the 0:10 and 0:58 sec marks you can hear The Shelbster grunt out a little bark too.
I checked around online a few weeks ago and I'm pretty sure it's the sound of a red fox screaming.