This wasn't a red card, but it was certainly a second yellow card. At this point in the clip O'Donoghue had already looked down at his broken stick, and turned his attention to checking O'Donnell. Easy yellow card.
@_hmck
Yeah I've seen a few comments to that effect and literally went frame by frame on the clip. A standard check from O'Donoghue, taking a stride into his path.
@kvn_clmn
If you watch the actual clip, rather than this useless pic you'll see the Cork lad braces himself for O'Donnell to run into him. What's he supposed to do? disappear.
It's maybe a yellow, but O'Donnell did him no favours with his cowardly theatrics.