Did you watch the video? This person didn't say it was impossible to launch enough satellites for Starlink.

He said the Falcon 1 launch price of $5MM was unrealistic, which ended up being correct. At the time, Falcon 1 was supposed to launch 600kg for $5MM. It ended up launching 420kg for $9MM. $8k/kg to $21k/kg.

Now obviously there's always a lot of doubt and skepticism around SpaceX, but you can just say "people said this would be really hard but they did it." Or you can say "Musk set a goal to 4x performance and got to an also-remarkable 3x" or whatever.

Even in this video, the smug Ariane guy heaps a decent amount of praise upon SpaceX and what they've achieved. He just said a $5MM launch will not be one of those things, and he was correct.