File:Strange thing (creature?) expands light then sucks it back in

Description
The strange shit happens around 1:05.

This happened at my grandmothers house. My friends talked me into uploading this as it's pretty strange. Basically I put my webcam on the outside part of my window. I was trying to get time lapse, I got a little more than I thought. It was taking pictures anywhere from every 1 to 3 seconds I'm not too sure. If you watch the light it shoots out of the back 3 in the lower right corner then it sucks it back in. It proceeds to move to the front light post. It shoots out and then sucks it back in. It seems almost as though it's some form of energy being sent out and absorbed back in. If anyone has any answers for me that would be amazing. Thanks for watching and helping me explain the explainable.