In club or high school sports, it might be easier to see someone in the stands with a camera video taping you. How did Big 10 teams know Michigan was in their stadiums recording? Do teams have someone with binoculars searching the crowds for someone with their phone or camcorder pointed at their sidelines?
An additional question is how did they match the seat with the person who bought the seat? I attended a D1 school and attended 2-3 football games but I don't remember my ticket having a specific seat I had to sit in. I will say, perhaps it was because I sat in the student section but people move around to "better"/"closer" seats at all sports games before the game starts, in middle of the game, or after halftime to seats that appear to be empty so how did they catch Colin Stallions allegedly stealing signs? Did he NOT move from his assigned seat and thus got caught? Was he totally careless and security caught him and took his id and stuff so they knew his name?