I'm sorry. I could have sworn it was the medium size in the video where she is running. The photo is definitely the large.Thanks! It looks like the large to me as well but I haven't seen either the medium or large in person, only the small and the tote (which is huge). If this is the large, it doesn't look too big on Kristen, who I believe is average sized (5'6"? Probably super skinny tho).