Yea it looks like a combination of a stretch, a scratch and some scent marking

. Have you got any further video from last night showing him walking around normally or running in his wheel?
It’s tricky doing a health check with a Robo but I think it will be less stressful for him than if you take him to the vets. I think mid to late afternoon is a good time - when it’s still daylight and when the hamster has chance to go and have a nap and still have a normal night afterwards to get themselves back to normal.
Could you set up a playpen area? Or use the bath? Somewhere safe for him so he can’t escape. A tip there - in the playpen, as well as a few toys to run around in, I also had a cardboard box - it was about 10” high a foot long and about 7” deep - just a handy size but any box will do if it’s tall enough he can’t climb out but I found that smaller size was good for handling him easily.
So in the box I just had a thin layer of bedding (thin enough so he couldn’t disappear under it) plus a little bit of scattered food and a treat. Then I turned the box in one side so it could be walked into in the playpen. That worked as after running round in the playpen (which can be a a bit of a large scary area for a robo the first time - he walked over to the box and walked in - a cosier area - then you just carefully tip it right way up again so he’s inside it- I had my hand the other side of the box so he couldn’t see a hand. He was happy enough in the box nibbling and I was able to handle him a bit in there and they get used to it then. You might find he goes very still once actually picked up and held and you can then turn your hand over so you can see his underside, but keep holding him low over the box in case he decides to wriggle free.
To get him out of the cage - I just started removing things and Substrate until Pip came out to see what was going on and had a mug on its side in the substrate - he walked into that to investigate which was handy so I just popped my hand over it and lifted him out that way.
If he doesn’t walk into a mug the easiest way is to probably just scoop him into the mug along with some substrate and put your hand over the mug then - it’s quick enough it won’t stress him and better than having to try and chase around with your hand.
With our first Robo who hid away a lot I literally had to remove everything from the cage to scoop him up. If that happens it can be an idea to leave them in the playpen for a while, while you set the cage up again.