i think you had no compression because you adjusted your valves without putting it TDC, which left your valves open, so you would be able to blow air into it. Try lining up the piston tdc then check the clearances. I know this is 4 years old, but someone else might have this problem too, and you should always make sure you're top dead center before touching any of your valves :)
When you blow in there and feel no resistance, it doesn't necessarily mean the rings are shot. It has to be at TDC on the compression stroke, if not your valve may just have been open. A leak down tester will tell you more, because you can hear and even feel where the air is escaping when the piston is up and the valves are closed. You may have set it to TDC before you blew in there, but I never saw it in the video. It can also be a valve not closing/bent that is causing all of the air to escape. What it DOES mean is one way or the other, you are going into the engine to investigate further, which does suck. Thanks for the video! I am working on the same bike, and you have helped me sort some of it out for sure!
I am preparing to do my first rebuild on one of these. Your video is very informative, and instructional. I will be referring to it as I attempt my rebuild. Thanks!
Dont boost a atv off a running vehicle. Good way to fry electronics. I seen the other video of it running and riding. So you got lucky. But it's usually what happens.