How does a Fluoroscopy work?

To use a fluoroscopy, the patient is required to in digest a contrast or fluorescent liquid such as barium, iodine, etc. This is how the internal organs appear on the x-ray video as the patient is being scanned by the beam of x-ray. Doctors can then clearly see movements and the organs clearly.

To work the machine, a technologist uses a switch to control the x-ray beam, which gets transmitted through the patient. The x-rays hit the contrast liquid which makes the organs visible and send the information through a camera to the monitor which the doctor is observing. Below is an image of what the image looks like in a monitor.   
 
This video shows most of the process