Apple iMovie and the Ken Burns effect

PSA: If using iMovie to create ... movies from screen recordings taken using [cmd][shift][5] be aware of the auto-cropping, including the so-called Ken Burns effect

https://support.apple.com/kb/PH22923?locale=en_US&viewlocale=en_US

I ended up recording clips several times before I remembered that I'd seen, and solved, this before ....

I wanted a full-screen recording of Terminal ( because .... I live there ) and iMovie was trying to be extra-helpful ......