I have seen the above videos in the past and have reached the conclusion that although these tank flushers and the pipe-mounted feedback rinser do help somewhat, but not to the extent I would prefer. We don't fret about it if we plan to keep camping.
After running our tank-mounted rinser for a few minutes and letting it drain it does appear that the majority of the tank solids have been removed. At least from our experience that isn't the reality of it with sensors still showing full in most cases.
If we really want the tank and sensors clean I go back and use a tank wand and it is amazing what is left after using our tank-mounted flusher. Don't do it every time, but if we are planning to let rig sit unused for awhile we use wand, sensors always show empty afterwards.
