[AcGold]

It's obvious what happened, he was going for a change and didn't see the play coming back the other way so close to where he was skating because the play had gone up the ice.

When he sees the play coming he also sees the ref all at the last second and lifts his hands to squeeze by the ref and the play going by. Just not paying attention, the puck unexpectedly goes by and Weidman most likely expected the ref to move some how. He was like a little dejected kid skating back to the bench to change off not paying attention at all.