@CaseyKinseyArt This guy, Dunn, may or not have jumped the fence with his accusation, but he is generally respected. Unkindness hasn't seems so unlike him, not his way. But I do think he should have gotten publisher and legal inform before tossing like that on social media. Sets a bad tone. And he says in his video that he had not spoken with Jake at the time. If wrong move by Jake, I hope he will do the honorable.
Also I don't think he is fully acquainted with the standards for copyright or trademark infringement as applied to media. The physical design, the wording, and terms used by him, and the images all must be given a proportion of importance. Perhaps the closest to his complaint is some similarities in the Tools and Alternate xxx pages.
Otherwise, at a minimum of 30 years of reading art instruction material and class handouts, informs me that I've seen and heard these concepts before.The various words used to instruct on line quality to sculpt, shape, contour a 2D image have been here forever.
I've followed Jake and Alphonso for years. So sorry to see this happening. PS: They both have admired and recommended each other.