hi bud. kl vid. thats quite a knock lol, who checked it over the garages granny lol
it sounds as though its in the cab going by the vid. heres a few common things i have found in the past and all easy to check, oh and by the way, im explaning it stupidley, not that i think you are stupid , i just dont know how mechanicly minded you are so bare with me lol
1st.. check the steering shaft, look under the steering wheel and just left of the clutch pedal you will se a shaft comming through the floor. this is the steering shaft [yay! lol]
now grab the shaft in the middle , and try and move it up and down, (eg towards the steering wheel and back to the floor) there should be none or very little play in the shaft. if there is play then this is your problem. all you have to do is tighten 2, 13mm bolts ,1 at the bottom of the shaft and 1 at the top, its ussually the one at the to thats loose.
2nd is a question? does your steering lock work?
3rd electric power steering collum, dodgey tourqe or giro sensors, though you will need the main dealer to diagnose this im afraid. also the steering racks are prone to this fault.
all of the above will give this symptom and are all common faults.
hope this has helped, mind and keep us updated pls and all questions are welcome alex.