The note in the video says she's (was) 9. The calculator in your link placed her into the 84th percentile and a healthy weight, while the note said 88th and overweight... BTW they're calculated the exactly same way, the ranges are what's different. edit: Even the video says she was 1 (ONE) lb overweight. That's a T-shirt and shorts, for example (not making this up, I've actually weighed mine). If she drank or ate anything before getting weighed, the difference may easily be 2 lbs which would put her into the 79th percentile.