When I turn up the roughness to 1, it completely goes away, but only because the surface is no longer reflective and is completely matte. I just want the material to look as it should (flexible aluminum tubing), but it keeps changing colors. I have point lights in the tunnel, and they're all the same temperature. Any thoughts? The still of the tunnel is how I'd like it to look.
The reason why the tunnel gets brighter and darker is because of the point lights that you've scattered across the tunnel. Areas closer to the lights (orange dots shown below) are brighter.
You can fix that by moving the lights with the camera instead of fixing the lights into a single spot. Delete all but two of the lights and parent them to the camera (yellow dot). It doesn't really move the lights perfectly along the middle of the tunnel, but you could always animate them manually to fix that.