Tom Felton: "I don't feel it's a responsibility [when fans queue and tell me their problems] but people told me things in this programme that were hard to ignore," he admitted to British newspaper Metro.

"I'm not a very good 'famous person'. If someone starts taking a sly picture I become very awkward - not because I am rude but because I'm not sure I know what I should be doing. Making this documentary has helped me understand who the fans are a bit more. It has given me an insight into it."

"[An older Harry Potter fan] came to mind when we did the programme. It was a chance to dig into her personal story and meet her. She's a sweet person, there's no malice behind it, but at the same time it's not something I fully understand and my mum still has her worries about people who talk to me as if they have known me for years," he explained.

"I wanted to find out what separates the passionate from the obsessive... people who wait outside hotel rooms and [who are] really into a certain project or music or whatever it is," he tells Newsbeat.

"When you see fans at premieres usually it's the same faces but you only see them for 10 seconds at a time.

"[But] they start to build up a relationship of support and recognition with the stars - it's hugely rewarding."

"People were dressed up as Stormtroopers, Gandalf and Dumbledore and my mates thought it was fascinating but also really weird," he says.

"Yet my friends were more than happy to dress up in a football kit and scream at the TV for Manchester United, even though they've never even been to Manchester.

"Why is kicking a ball into a net any less weird than liking a fictitious wizard?

"For things like sport or music, it's considered cool to be a superfan but as soon as it goes into Star Trek or My Little Pony or something a little bit obscure, it becomes a bit weird and people are keen to look down on it."

Daniel Radcliffe: 'It's definitely a weird thing when are aware you account for a large part of someone's life who you don't know and who doesn't know you - but thinks they do.

'Having an obsession with a character in a book is fine but when you are obsessed with someone you don't have anything about... I'm more comfortable with people being obsessed with Harry Potter than obsessed with me.'