This is of interest because of the GE BT-25-A transmitter footage. I do not know the serial number of the WCKY BT-25-A transmitter, but it is looks identical to the old WPTR BT-25-A unit which can be seen in this post. As I stated in that missive, I have not heard any transmitter before or since, that sounded as good as this unit. They were really engineering marvels, even in 1999 when this video was shot.
No doubt the MW-50 (no letter) and particularly the DX-50 transmitters are more efficient. In this day and age when many AM stations are just scraping by, over paying for utilities is not an option. I noticed the Harris MW-50 transmitter with the PDM drawer open. That brings back memories too, those PDM boards where a pain in the rear, as I recall.