Well.... Lesson learnt I hope. EWP's of any type are not toys. If your cast were worried about the scaff, explain how it was errected by trained personal to be structurely sound, and has a number of safety elements - like cross struts etc. Don't say "Look, I'll do some stupid stuff, and if I don't get hurt, well obviously your non-stupid stuff won't hurt you." frankly, that's daft, and if you were in a venue I worked, you would find yourself outside pretty damn quickly.
Whilst I understand you are learning the ropes of stage management and I don't want to discourage you, pull your head in. Theatre is dangerous. EXTREAMLY dangerous. Actors tend not to realise just how dangerous it can be. You have high voltages, with high currents. You have heights, and you have bloody heavy things suspended at heights. You have bars which only stay up there because they are counterbalanced with weights and secured with a rather weak break leaver, you have trip hazards and low hanging stuff.
There are hundreds of ways a person can be seriously injured in a theatre, and part of the SM's job is making sure that those hundreds of risks are minimised, and their hazard reduced. Part of that is to lead by example. Another is to instruct people in the correct proceedures within the venue.
Let's do my favorite piece of analysis on your actions.
Action: Jumping off of Scaff tower.
Risk: Incorrect landing leading to injury.
Likelyhood: High
Hazard: Moderate
Method to reduce risk: Do not jump from the scaff.
Risk: Misjudging distance and landing in the pit, atop music stands etc
Likelyhood: Low/moderate
Hazard: High
Method to reduce risk: Do not jump from the scaff.
Risk: Feet getting cought on kick board, giving jumper spin, resulting in incorrect landing
Likelyhood: Low
Hazard: High
Method to reduce risk: Do not jump from the scaff
And you could keep going.