This play was all the talk after my college game.
We haven't moved the uprights off the goal line, and the ball remains live on wide field goal. (In the US, a wide field goal will be out of bounds.)
We also don't have near the restrictions as US football does. (We allow our running backs to twitch their pinky finger. And for that matter, to be in motion towards the line of scrimmage.) We also haven't taken out of the game kicking at any time. A ball that is kicked into the end zone and goes dead in the end zone is a rouge, worth 1 point.
So when Montréal kicked the ball in, Toronto had to make sure that the ball didn't go dead in the end zone - no matter what. That's because this was the last play of the game: no time to make up for Montréal's hopeful 1-point lead. So they executed the "return kick". The punter and those behind him are onside and can recover. Offside players must give a 5-yard halo to the receiving team. (This rule replaces your fair catch rule.) Toronto had 3 guys in the 20-yard-deep end zone, including their kicker: Noel Prefontaine.
Montréal kicked the ball back into the end zone, hoping again for the rouge. Toronto's attempt to purge the ball from the end zone is called a dribbled ball (since it was loose) and this attempt failed, as Montréal kept the ball in the end zone and ultimately earned the touchdown, instead of the rouge.