I reckon the quick version, which worked for me and should for most others is:
1. Make sure you put the ball or toes of your inside foot on the peg, NOT the middle of your foot. Slide it back! You want your foot out of the way.
2. Get in the right position, similar to what old mate on the video says. Hang off the thing quite a bit, with your ass and your upper body and head all well off the bike .
3. Go into the corner quick enough to lean the thing over a decent way. No sense in trying to crank it over if you are going so slow that you will run off the inside of the corner. Just nice and fast but not insane (that comes later lol).
4. Once in the corner crack the throttle open, even if it is just a tiny bit. Being off throttle will just make it feel like the front will tuck so get used to having the throttle open a bit.
5. When you have got the above going on and feel good doing it, and your knee is still not down, you need to just drop the show a little further. So after you have cracked the throttle open, just nudge the inside bar a bit. It should not need much if all else is going well. Just make sure your knee is out but not reaching for the ground, and the ground should come up to meet it. And by nudge I mean nudge, you do not have to smack the thing. I do not want to be held responsible for someone coming unstuck, in fact I don't want to be held responsible for anything in life because quite frankly I am irresponsible....
As is the custom with these things I guess it needs the disclaimer that the above is merely my opinion and is not to be taken as advice in any way, shape or form, yadda yadda, yadda, yadda. You get the picture.
This should work for most people, I have short legs and ride a big bike so need to have the bike fairly over to get the knee down, so unless you are under 5 and a half feet tall this should see you smiling.
At first you will have so much fun with it you will probably grind your plastic knee sliders to death in a single day (or session if they are soft ones lol), and then you will be over the novelty part of it and just let it drag where it needs to.
These days I only really touch my knee down at the entry of a corner and sometimes on exit, and I also use leather knee sliders. I do miss the cool noise of the plastic ones though. I could simply stop picking my knee up mid corner if I wanted to, but for some reason that is what I seem to do now, particularly in a race. I seem to go faster doing it (but that's just me, individual results may vary as they say lol), and atleast I don't have to fork out money for knee sliders any more hehehe.
Anyway to further boost my already over-inflated ego
, here are a couple of pics to show my body position. I - like pretty much everyone else here except Josh Waters - am an amature and far from perfect, so a pic of an amature rather than a legend like Troy Bayliss etc., is probably more helpful and realistic. Plus I get to feel all grown-up like hehehe
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in one of the videos there are some girls there to keep you interested, 
so I have been told, well that is enough typing 
Guys would have their knee down while I was overtaking them on the outside going way faster.... very frustrating....