James, I don't think you can use ''learning to kiteloop'' and Len10 in the same sentence
Ruben is performing the most extreme from of kitelooping i.e. megalooping which is essentially a slowed down massive kite loop with a very wide arc, which can only be done with lots of height in your jump.
Kiteloops are dangerous and it's an easy way to get hurt. Learning to downloop is the first step, by going downwind in a transition in low/moderate winds.
The single most important tip with any loops is
commitment. As I mentioned before, the faster you loop (the more you commit) the less aggressive the loop will be and the less pull it will generate. Kiters learning to loop often don't commit enough which makes the kite go on a wider arc of rotation and develop heaps more power.
Small kites (less than 9m) and C-Shape kites are best to learn to loop as well as they turn very fast. I find kiteloops on Bow kites and Delta kites to be difficult and somewhat pointless/dangerous, especially on larger sizes.
IMO to learn proper kiteloops you need to be on a C-shape kite.