It might be something to do with my dodgey soldering, but I can't see any problems other than that. The clicking is it moving the motors very slightly although you can't really see that in the video.

I don't have an rx battery, but I did try it using the XL's BEC and got the same result. As for the radio, I was using it on Daiske yesterday and it was working fine and also works fine on the XL when they are both wired up. As for the receiver wires I haven't checked them but I will give them a look over.