Heck if I know. I'd assume the NCAA requested that every affected university pull their crowd film for the seats Stalions had purchased tickets for. i.e. Who was sitting in those seats and what were they doing?
They'd also need to review any in-person scouting videos that Michigan was using to prepare for a specific game.
If 19 months is a long time to conclude an investigation into something that spanned 3 years of illegal in-person scouting then I'd be pretty nervous that it's deemed more than a just a 'minor violation'.
The draft of the NCAA's notice of allegations called the alleged scheme "premeditated" and "deliberate."
Michigan already confessed to "Failure to Monitor", which is a Level 2 violation.
Not all Level 2's are 'major', but the data collected from this in-person scouting violation was intended to give Michigan a competitive benefit against their opponents.
Michigan is trying to keep this minor with imposing their own 2 game suspension on Moore.