Inherent to any discussion of "is X good/bad for the environment?", there's always the matter of accounting: to what or whom -- and when -- do environmental benefits/impacts accrue? And there's no general answer to that, which is why multiple reasonable people in a room can independently conclude that the solutions to climate change can be any of: personal responsibility and personal consumption taxes, the downfall of capitalism, public policy to distort market forces, laissez faire and light-touch regulation, domestic manufacturing, offshore mining, or even all of the above simultaneously.
Unless there is agreement on how the climate impacts are counted and totaled up, you'll get 11 answers from 10 people. I think the point of this video is: 1) in proportion to either the typical Western consumer or the average human anywhere on earth, the embodied carbon footprint from manufacturing of an ebike is low, and 2) the propensity to displace other modes of transport is where ebikes can flex their environmental credentials.
Some may not agree that displacement is a net positive, arguing that if an ebike works so well for someone that they sell their car, then that car will be driven by someone else and now there's an extra ebike in this world. I don't agree with such simplistic logic or its conclusion.
But for people that do see displacement as a valid environment net-benefit, then I hope they'll see that ebikes are very effective at that. Since ebikes still use lithium batteries, that'll continue to be a point of contention, but given the typically fossil-fuel alternative, we could do much, much worse for the environment.