There is imaging but not from a camera in the body (blood is not exactly transparent).

It's a form of x-ray video with a tracer in the blood, so they can observe both the guide and the blood irrigation.

The doctor will use live x-ray pictures to carefully guide the catheter up into your heart and arteries. Dye will be injected into your body to highlight blood flow through the arteries. This helps the doctor see any blockages in the blood vessels that lead to your heart.

A guide wire is moved into and across the blockage. A balloon catheter is pushed over the guide wire and into the blockage. The balloon on the end is blown up (inflated). This opens the blocked vessel and restores proper blood flow to the heart.

Source: https://medlineplus.gov/ency/article/007473.htm

My dad this operation in 2013 (and in 2007 before that), and I was allowed to watch it with his cardiologist (who was not the surgeon). They keep you awake, just insert something through the wrist. All the while you can just watch the insides on a TV. My dad reported that the only "weird" feeling he had was some sort of bubbling in his throat. He complained real time, and the doc said it's fine. Off Topic: The stent cost INR 150000 (they give you the box), but the hospital procures it for way cheaper. My dad's entire stay cost slightly less than that.