There's a legitimate argument for bias in Digital Foundry because unconscious bias exists regardless of intentions, but this is hardly 'proof' that Digital Foundry is being paid by Microsoft to play softball with them. The fact of the matter is that the PS4 Pro is a weaker piece of hardware (even if developers don't always take full advantage of it) than the Xbox One X and games with similar optimization on both consoles will suffer on the PS4 Pro. This is by and large an objective fact. KingThrash sounds like a conspiracy theorist on this one and I can only imagine that any discussion on the topic will lead to console warring because, well, that's what he's doing in this video.
You should consider thinking carefully about KingThrash's argument and whether or not it should shake your trust in Digital Foundry as an entity. I think the point he presents is weak, misleading, and draws a more dangerous conclusion than any real evidence he presents actually supports.