Trying to understand why rotating the casing is better than rotating the screw, and I can offer the following explanation:<br>1) If you rotate the casing, the main friction forces opposing the lifting of the product are on the screw. The product gets rotated by the casing up and around the screw (note in the video how there is no speed difference between the seeds and the casing - they rotate together), and so leakage down the gap between the outside of the screw and casing doesn't occur. If you spin the machine faster, the product is pushed into the casing and away from the screw (centrifugal force), making it more efficient.<br>2) If you rotate the screw, the main friction forces opposing the lifting of the product are on the casing. This stops the product from rotating with the screw, instead it gets pulled straight up the tube with greater losses, and leakage down the gap between the outside of the screw and casing occurring, which will result in blockages. The faster you spin the machine, the greater this friction becomes and the higher the risk of blockages as product gets forced into the gap between the screw and casing.