Disclaimer: I'm mostly pro-Ukraine but acknowledge valid Russian points, though in my opinion do not justify this invasion.

I watched all of Lancaster's videos. I think he in the beginning he was clearly pro-Russia. But with time in a very subtle fashion I believe you could see him questioning his original views. He would ask questions such as "How do you know there are no civilians at these coordinates, have you confirmed this?" to artillery soldiers and the response would be something along the lines of "No. We don't check. We just trust there are valid military targets at the coordinates provided to us." As a result of these instances, I think he slowly started to change his mind.

In later videos, and this is my conspiracy theory, he would actually have information in his videos that I believe were tactically useful to Ukraine, e.g. munition locations, but in a "playing dumb" manner. If so, I wouldn't be surprised if at best the Russians just stopped allowing him to film behind enemy lines or at worst apprehended him.