I think the vehicle shown around 15.00 onwards is a trackless Christie M1931 or one of its derivatives.
Cracking stuff, Dave. And I think there may be at least one other Christie there in the form of a car that looks very like one of his racers. Might have to get some screen shots & see if we can't work out what they all are.
There is the Christie Motor Carriage for 155mm Gun and as Ewan has said the M1931 and I think also the Christie Light Tank M1932. Other tanks that appear are the Mk VIII Liberty, the Six Ton M1917, the Medium Model 1922 and the Medium T2. Other things of interest are a Fokker DVII and a WW1 German heavy artillery tractor.