Okay, now what is Let’s Play, legally speaking?
From a legal perspective a Let’s Play video would almost certainly constitute a derivative work under domestic and international copyright law. A derivative work, for the uninitiated, is a work that is based upon one or more pre-existing copyrightable works that recasts, transforms, or is an adaptation of those works. Examples would include cinematic adaptations like Twilight, The Hunger Games, and Ender’s Game that are based on best-selling novels, as well as things like translations, musical arrangements (which are adaptations of an original score), editorial revisions… Basically anything that adds new, creative, and original elements to the underlying work regardless of whether those new elements are separable from the underlying works.