If you're on facebook, look at this Matt Vincent video. (best watched in Google Chrome)
https://www.facebook.com/matt.vincent.961/videos/vb.1385872905076066/1456719024658120/?type=2&theaterThanks for posting your video: When the weight comes around in front of you during your cast, the first part of the movement, you keep it low. It should be higher above your hip. You need to keep your left foot up on your toes. That will allow you to rotate into the different positions.
Also you need to drop your arse with the weight. When the weight is down, your butt is down. When the weight is up, you are up. Your legs make the weight move, not your shoulders.
The 56 is the toughest weight to learn how to throw, because you have to wait on the weight to get to the next position. You also get tired quicker. You may want to work more with the 28 for proper positions with your feet until you have them down pat. Just my 2 cents.