Good advice from above, my level 3 was about 12 years ago, so no video necessary. I was monitored on the job though which was nerve wracking!
Most important things to remember:
Just be you, don't try to be an idealised version of yourself.
As mentioned above progressions and regressions are king. Sometimes players will struggle or excel due to skill, but mostly it's due to a communication issue, if things aren't going great don't be afraid to drag them all in, ask what the issue is and find out what is going on.
People think planning well means everything is going well all the time, it isn't. Planning helps you make adjustments when things go well or most likely wrong. Sometimes planning a specific activity where players struggle helps you look strong when adjusting that issue.
Most importantly, the difference between level 2 and 3 is your ability to create an environment of learning. Any level 1 and 2 coach can prescribe drills and make positive noises, having the confidence to let go of the reigns, and putting players in a position to make decisions is key. Just make sure your emphasising behaviours and outcomes conducive to a positive.
Good coaching is good theft, don't try to reinvent the wheel, don't feel you need to come up with original sessions, just use what you know from great guys you've worked with, and improve on them.
Going through level 3 really does give you an insight of what type of coach you want to be, see it as a learning curve, and not something you stress about passing. Whether your an off the cuff chef type who adds spices and tastes and adjusts as you go, a technical genius who really digs into the detail, laid back jazz environment or high intensity control freak. There is no right or wrong, there is you and not you!
