Do you have a lot of time FPV? in the video I'm noticing you drifting left towards the bank, like you were flying at an angle under the bridge, you had much more clearance in the center. You can see the bridge is curved with less clearance to the water on the ends. Looks like the ceiling came down to meet you, and not you gaining altitude. You are one lucky dude, it could easily bounced off of the bridge and directly into the drink.