Pedals turn but bike doesn't move
Judging from your videos, it appears that the chainrings and crank are no longer connected. It appears that you have something called a one-piece crankset. If you are confident that you can learn how to disassemble it, I’d say you’re up for the repair.
Once you have the crank off the bike, you’ll be able to see how the chainrings and crank arm are connected. Assess the interface. Is there a threaded ring that may have come loose? Be aware that the hole mounting the chainrings to the crank arm is a D shape, and the fact that it’s able to spin like that may mean that the D shape has been destroyed and turned into a full circle. In that case, the crankset is likely not repairable. A welder could fix it though.
Let me know if you get the cranks off the bike, and then we can go from there. As an aside, your cable routing seems iffy: are there no braze ons to tie the cables to? I don’t believe a bike manufacturer would just zip tie the cables around the frame like that. It’s not an issue other than cosmetics though. It almost feels like the brakes are mismatched too. Why is the cable looping around itself like that?