I 'm not sure if I have to much pressure on my back foot or I'm just a gumby the fin let and i could not get it back, what is the best way to get it back ? Can this be avoided. It's not fun sliding sideways even at my slow speed.
You were sailing with windward rail down !!! which means you need a bigger fin so you can get a lot more power out of the board. Board should ride on the fin a lot and leeward rail is more in the water.
When you spin out you can pull your back foot to windward and sheet out at the same time as you need to re-attach flow over the fin again.
Looks like it is just too small in the video.
Try using the rig raked back instead of so much foot pressure to steer the board.
It looked like you got the board in the air launching off the chop, landed with a lot of pressure on the back foot, staying sheeted in. This caused the fin to let go (only half of it was in the water just prior). Were you feeling overpowered? How do you find it when it's smoother water?