*Bob Uecker voice*

Just a bit offsides.

Or you can save time by reading the title of the video and listen to the audio.

There's missing a call (just not seeing it and making no signal) and then there is completely blowing a call (seeing something and calling the opposite).  That linesman should be fired immediately for calling that onside, he clearly waves off the offside.  WTF?

The first time that I looked at it, it appeared that the defenseman had mis-played the puck back  into his own zone.  Did the defender(s) not play the puck, did it just bounce off of them, or did it just change direction as it hit the ice?  It does appear to hit the first defender, and the second does attempt to play the puck, and it changes direction as he attempts to play it.  I don't think he "carried" or "passed" it back, though.

"If a player legally carries or passes the puck back into his own defending zone while a player of the opposing team is in such defending zone, the off-side shall be ignored and play permitted to continue. "