Starts at about the 6:05 mark.
https://youtu.be/f-Jp59Liehg
For my part, I can think of two egregious blown calls:
2005: TCU clearly fumbles into the end zone in overtime. Should have been a touchback for BYU, and a win for BYU. They call a TCU TD instead, BYU loses.
2010: Brandon Bradley intercepts a pass by Utah’s QB at a most crucial moment in the game. His knee is clearly down with possession, but then he loses the ball. Refs call fumble, BYU loses the game.