I did not show that in the video, but I cleaned up the burrs with my spring hook. A better way to do it would have been to install the water key before I soldered on the crook. That way, I could have cleaned up the burrs from the inside with the triangular knife. But I did not think of that until it was too late.
The slide trumpeter (I am not sure if that is the correct term) tried to play it, but he was having problems with the positions on a different slide trumpet. He took it home to practice it. I am planning on publishing the last video this Friday.