What are BTZS Tubes? As the video mentions, they are tubes from Phil Davis the writer of the book, Beyond the Zone System.
OK, so this 4×5 Part 1 video is a bit strange, but it shows BTZS tubes in action. BTZS tubes are tubes used for sheet film development.
4×5 sheet film development in BTZS tubes Part 1: This is the “classical” video
4×5 sheet film development in BTZS tubes Part 2:
Here is the 8×10 sheet film development in BTZS tubes video:
These were from Fred Newman at the view camera store.
