What tuning does she use here?

I'm new on the 5-string banjo. So far I have only played in regular open G tuning, and then the G modal tuning (where the 2nd string is tuned up half a step). Now I want to learn how to play this tune the way that Leah Song from Rising Appalachia does it on a 5-string in this video: https://www.youtube.com/watch?v=L68UUv4Bw-M

I don't need a full tab. I can make out what she plays by ear once I figure out what tuning she is using. Can anyone figure help me figure out what tuning that is? I'm struggling here. I hear someone talk about double c tuning. Is this what she uses? Or something else entirely? Help much appreciated. Thanks.