First: Ali, I tried to push the lever all the way in. Ignition was off, and the starter was spinning for a second one time. I also tried to start it while the lever was pushed all the way in, but no difference.
Kevin: I am in Norway..

It has gone from working just fine to doing as in the video in a few days with (stupid me..) a lot of work for the starter, trying to start with the gas crane in On-position, when it should have been on Res...
I have removed the engine oil, and will check behind the engine cover tomorrow if I can find the time.
Earlier I did remove the starter, and looked at what I believe must be what you are referring to as planetary gear, after googling it..

Now I only remember that I pulled out the gears and looked at them, they looked okay, and I inserted them back in. I believe it was possible to rotate them manually, but I am not sure.
I will anyway try to look for wear on the clutch, and see if I can get closer to a solution. Will update when done.
Thanks to you both.

I havent done any mechanics for 25+ years, and then it was only on my Yamaha DT50, inserting a big(ger..) bore kit, going from 2.5 hp to 7.5 hp, which was fun enough, and some other minor stuff, so my knowledge and skills are on a very low level, and I am grateful for your patience.