The only one I know of is Railstream. They have a camera that shows the BNSF line where it makes a sharp turn to & from Union Station. It shows all the trains using the BNSF Aurora line plus those trains using the St Charles airline. It does require a subscription to their service.
The Santa Fe Junction in KC, MO has two cameras. While it is mostly designed for freight trains, the Missouri River Runner and the SW Chief also use this junction. There is usually someone on the chat that is manning the cameras when the Amtrak trains are there and they make sure the trains are not missed.