As someone who has heard the name "Jack" pronounced by Americans many, many, many times in their life... that Jaques video sounds entirely in-range of the variety of pronunciations I hear for Jack.
Well, as one particular American, who has spoken to many, many other Americans in their life, I can only tell you what I think.
Something I find interesting is that Americans say the a in the word taco (a word borrowed from Spanish) with the a as in father, that is, [ɑː], but English people say the a as in cat, [æ]. Different dialects approximate the Spanish [a] differently.
