My area is WWI and its immediate aftermath, so I can only speak with any authority on Episode 1. It takes a different approach from that with which English-speakers are familiar, but manages to convey the broad sweep of the story. To begin with the Austrian Gunther Burstyn's Motorgeschütz is unusual but an argument can be made for it. On the other hand, there's nothing to support the implication that Burstyn's vehicle in any way influenced the French or that the French had even heard of it.
French bias? Well, all three writer/producers are German and live in Germany, but the production companies are, I think, French. It should be remembered that French and British tank development took place at the same time, so to begin with the French story is perfectly justifiable, if unusual in the English-speaking world.
The Episode's biggest problem is that is littered with historical errors large and small and makes some dubious and debatable assertions. Soldiers described as Austrian are actually Italian, and supposed Germans are Austrian. The British tanks are shown in a completely random chronology, but that's quite usual in such documentaries. On the other hand, a lengthy reference to the French Renault FT is accompanied by film of the American Ford Three Ton tank, and what we are asked to believe is film of a battle on the Western Front is actually footage of manoeuvres in the USA in the 1920s featuring tanks that didn't take part in the War. Producers of films on this subject often have to make do with such material as is available, but one gets the impression that this one contains howlers that the makers just haven't spotted.
So this just about keeps pace with historical fact, and it might be that the layman would not be troubled by many of the inaccuracies. Good use is made of the diaries of tank designers and commanders (a few odd translations notwithstanding) and the Curator of the British Tank Museum gives a good performance as in-vision commentator.
On the whole, this is let down by some poor research and careless production. I wouldn't recommend that anyone use it as a serious reference. A missed opportunity.