“David Attenborough” (a soundalike voice) explains the Cybertruck's parasitic relationship with flatbed trailers; transcript:
Here we see the Cybertruck has formed a peculiar symbiotic relationship with the larger flatbed trailer species. Evolutionarily disadvantaged, the Cybertruck has come up with a clever way to transport itself long distances.
By attaching itself to the flatbed trailer, the Cybertruck can reliably move about without risking injury to its fragile exoskeleton or internal organs. What the flatbed trailer gets in return for this kindness, science has yet to discover.
Source
I wondered who had made the video and found myself on Reddit, in r/CyberStuck, where the video was originally posted. The creator of the fake Attenborough video, who has since deleted the post, explains in the comments that they wrote the script and edited the video, and for source material, they used "a bunch of Cybertruck fanboys on YouTube, Whistlindiesel, and also the lovely people on this fair subreddit."