who else filmed part of this?

During the part at the end with the interviewer she said that that that particular interviewer had been following her, and I believe that she had been instructed by the producer on filming herself and shots to get and such, so it's possible that there were different people at various checkpoints to film certain things. I haven't seen anything confirming it, but it could happen. I know that some people who have their own travel/documentary shows will set up scenes, walking somewhere and putting the camera down/on a tripod, then walking past the camera so it looks like they are being filmed by someone else. It's possible that she was taught some basic things to do all of it herself.

At her first stop at Canary Islands she says she met up with others. As she had sponsors and a film crew doing the shots on land (it said at the beginning the producer filmed most himself except those at sea). So while at sea she filmed herself under directions given by the producer of the documentary but while on land she would meet up with her film crew or sponsors and they would help film.