'Harry Potter: Return to Hogwarts' takes a magic-filled trip down memory lane

HBO Max has developed a fondness for reunions after that awkward "Friends" gathering and "The West Wing" voting special. Yet "Harry Potter 20th Anniversary: Return to Hogwarts" strikes just the right balance, looking back at the cinematic franchise with warmth and humor, while delicately capturing the impact on kids raised on a movie set over a formative decade.