So we took advantage of the nice weather and decided to brush the stack. All of my 8" pipe is over 40 years old. Every year I have lowered a light to look as best I could but I have always wondered. This year I strech wrapped my cell phone to the rod and took a video of the inside of the stack. I poked the rod through the center of a coffee can lid to keep the phone reasonably centered and just lowered and rotated it. It works pretty decent.
I tried doing that before I knocked out my clay liner. Unfortunately my camera stops recording as soon as it got in to the dark portion of the chimney. I tried turning on the flashlight but it didn't work with recording a video.