I can pass along one tip based on personal experience: Whatever you do, do NOT remove the spring that is inside the lever. You'll need to build a tool to put it back in. It's like a clockspring, but angry-ier, and impossible for a layman to reinstall to a level that only a German engineer could have devised.
I took that spring out, and got it back in without tools... but it was really frustrating, and I had to walk away from it several times and come back to it later. Almost gave up and sent it to someone to fix, but I finally got it.
It's doable, but it sucks.
FWIW, that vid is the early style... the F style and the intermediate style have a different setup for the latch and spring.
A forum dedicated to and laser-focused on Heckler & Koch firearms, Heckler & Koch accessories and the owners and enthusiasts that love them! Come join the discussion regarding HK pistols, long arms, NFA arms, HK accessories, HK history and trivia and more.