I saw what you saw Quint, except only Crosby can say whether he got concussed by the OV head slash or the Niskanen cross-check on his way down.  
Even if the concussion happened on the Niskanen cross-check, it was OV's reckless head slash that threw off Crosby and lead to the concussion that has potentially dealt a severe blow to Pittsburgh in these playoffs and maybe jeopardized Crosby's career.  
Now I have two teams to really hate in these playoffs...Ottawa and Washington