Sxyglock,
The rounds consist of a 35mm film cannister with a couple of flat washers in it for weight, filled with flour, and topped with some red chalk.
About 80% of the rounds make it downrange and "burst" when they hit the ground.
About 20% lose their lids as they leave the bore, and show up like the one you saw in the video.
Max range I've gotten is about 150 yards with one of these, on top of 55.0 grains of FFFg Blackpowder and a 209 Shotshell primer.
The film cannisters will simply punch through a core-plast plastic target face.
NS