v. In ice hockey, it means to barely miss a goal when a shot eludes the goaltender, yet deflects back into play after hitting either the left or right goalpost. A hard rubber puck shot at high velocity makes a "ringing" sound, much like that of a bell, when it hits the metal goalpost, thus...
At 1:25 he elaborates on that mentioning she sent a ring to her ex. "A ring In the post" would mean she "put it (the ring) in the post" (sent it to him).