Not only do we see the early  C40A WT in action but are clearly shown how the WT drives the hands of the very large dial via lead-off work and the motionwork gearing.
An early feature is the lack of a roller on the pendulum drive armature. Later movements have a roller which pushes up against the impulse pallet. [i.e.The hook shape which extends to the right from the pendulum rod.] Despite the very obvious hook the drive armature only pushes upwards against the curved impulse slope between the hook and the tip of the pendulum extension. The hook itself is a red herring and never contacts the impulse pallet or roller despite appearances.
The time setting handle is missing from the front end of the worm and ratchet wheel shaft.
The contact assembly support post is oval, fixed and the major axis is horizontal. This is the opposite of later WT movements. Which have slots in the base plate to provide for horizontal adjustment.
The second video is from Clockworks: This has already been covered in an earlier post but is worth mentioning again:
The deeply curved cutaway in the masking pawl of the waiting train mechanism is later. Despite the age difference this movement still has deep gold lacquered, brass components and the "bent knee" to the main frame casting above the power electromagnets. Later movements had a straight bar just above the large coils.
This movement still has the lacquered, cast brass, contact steady bars. Later movements had pressed steel, contact steady bars with more gentle curves instead of abrupt bends. Many components were plated steel in later movements.
Some earlier WT movements may have had their contact assemblies replaced with the later design during routine maintenance. One must then look to all the other design features for a better confirmation of age. Unfortunately the earlier black and later greeny-blue paintwork may have been painted over at some time. Though it may still be possible to find remains of the original paint in very inaccessible places. Particularly underneath. Though one should not deliberately damage the present paint in a search for the original.
The pendulum drive contacts are rather prone to oiling if the clock minder is too generous with lubrication to the Hipp toggle and V-block. Running a cloth with a suitable grease solvent between the contacts while they are pressed together may help. [Do not leave potentially combustible rags or fluids in the clock room! Some solvents can spontaneously combust if rags are left exposed to the air!]
The pendulum should really be brought to rest and the drive power switched off first before any maintenance. There is a serious danger of trapped fingers if the WT is left running. Not only from the heavy swinging pendulum and its cast rod but also from the drive armature. The large electromagnets have considerable power to trap unwary fingers via the rocking armature when activated. [Either accidentally during contact cleaning, oiling or during normal running!] The WT and its clock hands are easily advanced to time using the time setting handle on the front end of the worm shaft. One need only watch the time setting dial advance past its pointer below as the crank handle is turned.