When fans of Harry Potter heard the line in the “Belle” clip, they instantly equated it to Harry Potter and the Sorcerer’s Stone, which features a scene where Neville Longbottom talks about a remembrall, noting the only issue with the device is that he “can’t remember what [he’s] forgotten.”
A short while ago, we learned there was a line in Beauty and the Beast that came from Monsieur Jean, who talks about having a problem, but one he “can’t remember what!”
Unfortunately, Bill Condon says the coincidence in the dialogue is just that–coincidence.