In my post above, I should have written gearbox main shaft not output shaft.
Anyway, looking at your video again, when you kick it over, the gearbox main shaft is turning and by viscous drag within the gearbox, the gearbox output shaft is turning causing the wheel to turn.
Are you sure the engine is turning? If it is, you have very little compression based on the apparent effort to kick it over. Or maybe you are kicking it over with the decompression lever activated??
There is an inspection cover on the primary (left) side. When you remove the cover you can see the primary chain. When you push down the kick start, does the primary chain move?