Diving off the rig should not be necessary, maybe just a pilot showing off to his pax
Falling off the edge of the rig was, and perhaps still is in some quarters, standard practice. I note your "should not" though Nigel.
Also is it usual practice to do the agressive dive off the platform coming within only feet of the ocean in order to fly out safely to gain speed I again assume for single engine operations
On a take off there is a period where an engine failure may deposit you in the wet stuff. Depends on environmental conditions and weight as to whether you can get away with it. Speed is life when marginal and beyond. With a failure in the 76 you can get very close and personal with said wet stuff in making a successful fly away, as in 5 feet, and that's doing everything by the book in relatively benign conditions.