Played the video & after 5 seconds its conclusive in my mind. Exhaust is blocked. Maybe not where you're looking in the end, but there's 20 horses getting strangled in there somewhere. To prove a point if you live rural, remove complete exhaust & give it a good full song rev & hold it there till it clears.. It's so bad that i'd eyeball the port while the pipe is off as not unusual for small motors to build up at the cylinder right as the piston goes by. Forget the timing or getting super technical about it,. just give them gap & fix exhaust then worry later about timing. Can't be too far out with points at 14--15.

Talking the marks--magnets do pull of course, but points should crack free [just start to part] as the marks on flywheel line up with casting notch in the case.
Also the casting mark for timing will be about 1.8mm [points 'just' breaking] before TDC. I know its Kawasaki but timing will be very similar to Yamaha 100.

Rotary Valve bikes ALWAYS PRESENT MAJOR CHALLENGES at least for me. They suck air - not only through the air filter - the right side case - and the fuel line going through the side case. When three areas are sucking air simultaneously ( which is bad ) you have a lean condition — a white spark plug and a poor running machine. Yama-Avoidance comes to mind after writing this post…

a negative