Thanks. It is not the usual bolt-in and bolt-out fix because apparently the bolts don't come out easily on this particular bike because of previous thread damage. And so I thought it is a good idea for a video.
Hints to make it easier: Loosen the front sprocket bolts before raising the rear wheel or breaking the chain. Twist off the larger diameter rear sprocket hex nuts and not the smaller diameter Allen heads.
Hi. Thanks for the useful hints. Regarding twisting the large diameter hex nut, I did that but both hex and Allen heads just rotate. There is thread damage that's why it is stuck.