ORD was busy & backed up pretty heavily on July 7 (I was there that day.) Plenty of inbound flights were holding, which is exactly what seems to be going on in that video. Not surprising that things ran late; too bad the connecting flight didn't run similarly late.
No need for the usual floats.
Floats obviously add both weight and drag so it is beneficial to fly without them. With the fuselage sailing like a ship, they are not required. There are some under the wings but tiny. They do not support the full weight of the aircraft.
But floats also keep the aircraft in expected orientation, raised above the water, same as ...