The video was captured by her godfather and posted to Twitter.
Pope Francis cracks up immediately when he realises Estrella's grabbed his skullcap - called a zuchetto in Italian - and takes it back with a big grin on his face. His press officer later told CBS that Pope Francis loves unscripted moments, and wants people to see him as a regular guy.
Scott laughed it off and said his daughter was a very independent girl: 'She does what she wants!'