I wonder if they inadvertently strengthened the conspiracy theory by doing it. Sometimes censorship has that perverse effect. I easily see someone hearing from their "friend" about how Amazon has removed the video because they know it's true, and how it just validates all the bullshit claims presented there.
It's a balance. Banning books has been known to make them more widely consumed, but reading is intrinsically less viral (and more informationally dense, typically) than watching a video.
I think it's easier to attain a critical mass of followers if these kinds of videos go unchallenged.
