At the UFC 278 official weigh-ins, all 26 fighters on Saturday’s fight card in Salt Lake City will step on the scale Friday, and MMA Fighting has live video of the proceeding that can be seen above. In the main event, UFC welterweight champion Kamaru Usman and challenger Leon Edwards can weight no more than 155 pounds, the maximum allowed for their lightweight title fight. In the co-main event, former middleweight champ Luke Rockhold and one-time title challenger Paulo Costa are capped at 186 pounds, the maximum allowed for their non-title middleweight bout. The UFC 278 official weigh-ins began at…