Wow, bat flies are bizarre creatures!
I went out to find one of these extraordinary ectoparasitic insects with my museum colleague, Lisa Gatens (https://naturalsciences.org/staff/lis..., as she was trapping and banding bats in the North Carolina's Coastal Plain. The bat fly in this video was collected off of a Southeastern myotis (Myotis austroriparius) bat and is likely the bat fly species Basilia boardmani within the Nycteribiidae family of flies (will update if I get a confirmed species ID).
Music from soundofpicture.com