Conditional clicking from back wheel
It does seem to be in time with your pedalling. If this is the case in any gear, then it would indicate the issue is in the pedals, crank, bottom bracket area.
Check it isn't the front derailleur cable clicking on the right hand crank... rule out the easy one first! The mudguard too, anything that could be rubbing that shouldn't.
Then you would check the pedals, crankset and bottom bracket one by one. If you can swap out the pedals then you can isolate them and see if the problem goes away. Then check the crank bolts are tight and that the chainring bolts are too. Then if not solved you can pull the bottom bracket and inspect it for play in the bearings, replacing it if necessary.
btw, can't see in the video resolution but it almost looks like the front derailleur is incomplete? might want that replacing sometime. If that indicates the condition of the bike (poor) then the bottom bracket could well be worn out and be a strong contender for the noise.