Oprah Winfrey's interviewees always worry whether they did ''OK'' in their on-camera chats.

The 63-year-old talk show host has interviewed a number of high-profile stars over the years, including former President Barack Obama, actor Tom Cruise and pop superstars Madonna and Beyonce, and regardless of the topics they cover, she knows there's always one thing guaranteed to happen.

Speaking on a panel at the Tribeca TV Festival, Oprah said: ''One of the great lessons, if there was a common denominator in the human experience of the ['The Oprah Winfrey Show], which was my greatest teacher all those years, to me it is that everybody that I ever interviewed, after every interview, at some point somebody would say, 'How was that? Was that OK? How'd I do?'

''And that is whether it was Barack Obama, or Beyonce, or the guy who murdered his kids, or the guy who molested kids, or somebody who'd been on and lost their family, at the end of every interview somebody would say, 'Was that OK?' ''

However, Oprah admitted she was surprised when even Beyonce needed reassurance after an interview.

She added: ''And after Beyonce. I go, 'Girl, you're Beyonce!''

Despite her global success, Oprah's first love was acting, but she recently admitted she finds working on movies intimidating.

During a conversation with her award-winning 'Wrinkle in Time' co-star Reese Witherspoon, Oprah admitted to being intimidated by the experience.

She recalled: ''I just finished doing 'A Wrinkle in Time' and I asked Reese, 'How many movies have you done?' And she said, 'Oh, hundreds. Hundreds.' And I was thinking, 'I think I've done five. I hope she never asks me how many I've done.'

''And I always feel a bit intimidated where you're literally taking on the life of someone else.''