I'm not an insider, I don't know all the specifics of the procedure the officials follow, but generally from what i've discussed with a couple of mechanics and observed myself at many finish lines the following happens.
Rider crosses line
Bikes tagged by UCI official for routine winners inspection and then random inspections too
All Podium riders then ride their tagged bike around to winners enclosure and begin warm down
Rider finishes warming down
Mechanics for each rider's bike called to attend bike inspection and weigh-in
UCI official gets mechanic to walk bike from winners enclosure to the inspection tent
If the X-Ray trailer is being used, the bike I think is x-rayed first and then bought to the tent.
Bike is weighed
Team mechanic then removes BB/Crank and seat post etc
Frame inspected for motors and batteries by eyes, endoscope, ipad etc
Wheels scanned with ipad for magnets and I think get weighed separately against known manufacture/model weights?
All riders on the podium, the mechanic and the UCI officials never really leave the winners enclosure and it's all visible by the public as you see in Contadors video you posted of his bike being taken for inspection after warming down as winner. Randomly tagged bikes with riders not on the podium or classifications, probably do end up back at the team bus first, but it's a random inspection nonetheless. Even if you get away with switching wheels or bikes when not a winner, as soon as you are a winner, your bike, the wheels and the rider never leaves the winning enclosure as far as I can tell, so I can't see how a mechanic or team staff could switch wheels anyway. As a winner you and your bike have a cameras on you for the whole time. Someone would have filmed wheels being changed in winners enclosure i'm sure, given the high profile motor-doping has.
Of course if you don't trust anything UCI does, then all of this is simply actors pretending to be officials and it's all a rather convoluted, expensive act, perhaps not even necessary for credibility anyway and that's not the reason UCI are doing it from what I can tell?