They were genuine reactions. That is what Beatlemania really looked like. Richard Lester put ads in the papers inviting fans to come to the theater and the kids got to watch the production for free. Spyders
I read an article recently by someone who was there. He said the concert shooting session took several hours, and that the hall slowly filled with the smell of urine as the fans couldn't 'contain' themselves.
Collins has either mis-stated his birthdate or is misremembering his age. His bio says he was born in January 1951; the concert scene in AHD'sN was filmed on March 31, 1964.