This is where it gets crazy. I don't want to be an online "detective" and send in some far-fetched crazy thing that only takes time away from an actual great tip. Then my thoughts go to, "no tip too small." I'm torn. I feel like this man in the video clearly knows this area and this video could be an example of that. The gait and everything about him. Clothes, etc. idk...?
A person who is involved with the save the Monon High Bridge (there's a Facebook page for the effort) has been reported to LE. Several times. Looking at the video, that may or may not be him.
ETA: Actually, the person in the video looks a bit older (70's vs. 50's)