I think you'll find that it's just the weight disadvantage here.
Not sure if it's been covered, but could see no mention of it.
But it's not a weight thing.
Well not exactly, ok the FL is lighter, but they still weigh 1.5 tonnes so are easily heavy enough to cause issues should weight be an issue.
No the answer is likely TCS.
To full appreciate this you need to understand how a diff works. But all classic RR's, D1's and pre TD5's have open axle diffs. This means under certain conditions they will not be able to send power to all 4 wheels but only the 2 diagonally opposite ones.
Also the clip looked like most/all where on road biased rubber, so combine this with open axle diffs and it's not surprising this was the end result. You'd have needed to pick a very good line or carry more momentum to get up.
A Freelander on the other hand has a very good TCS system, which will brake a spinning wheel, this applies load to the wheel, load causes wheel HP to increase (like a Brake device that measures Brake Horse Power, hence 'B'hp.).
This increase in wheel HP forces the opposite wheel to rotate. The distinct advantage is the Freelander can make all 4 wheels drive the vehicle forward rather than just the 2 with the least grip. The TCS simulates a locking axle diff, although in someways is superior as it can continually adapt in a more precision manner than a locking diff that simply forces the same wheel speed on each wheel at all times.
However in this instance is proves that technology can make a vehicle like a Freelander superior on a surface like this that was all about traction rather than ground clearance and axle articulation.
Wet grass, snow or sand would likely yield similar results.
