Sorry, I misread. Actually, I translated it in my head to Hebrew and back to English so what I wrote made perfect sense in that case.
Anyway, I should have paid attention better.
Regarding the bouncing, it's most common either for the first throw ("Bend your knees and go for it!") or continuously in sync patterns.
I'm not sure what you mean about whether it's acceptable. I've never heard an opinion that it's not. I can only guess that it might be a WJF thing?