The spelling of words which are meant to illustrate the difference between US and British, are rendered throughout in the US version only, and some spellings are not the word spoken. If you can't get that right why bother.
Pure baloney! There is no American radio personality named Bradley Tanner, and the only book I could find by Margaret Whitmore, is on repairing old sewing machines, not on the history of the English language.
What said in this vid is probably true, but invention of two people who should have be rather known in their countries (quickly checked and found fake) casts everything in bad light, it looks like "these assertions are weak, so I'll give them strength creating experts to validate them"