WWE has confirmed to Alfonso Castillo of Newsday that Matt Hardy "was pulled off the card" of the last show of the European tour as well as the White Plains show a week earlier, but declined comment "as to why." Castillo's whole post is well worth reading if you're a Newsday or Optimum Online subscriber.
I would say that the most interesting passages other than the confirmation are these:
"The slurred speech. The sleepy eyes. The erratic, stream of consciousness statements. Far be it for me to make any accusations, but I think most any honest and informed observer would have reason to be concerned about Matt’s condition in this video.
Perhaps the biggest 'tell' that Matt Hardy has a problem is his adamant denial that he does. The hyper-defensive, insistence that he feels better than he ever has might sound familiar to most anybody who has ever dealt with any kind of addict."
"Most bothersome about this story – as with so many stories – is the refusal of fans to listen to anything negative about their favorite WWE superstars. Go through the hundreds of comments on the Youtube page where this video appears, and the vast majority are along the lines of 'We love you Matt!' and 'Good for you!'
It’s great for fans to be supportive of Matt, but doing so shouldn’t mean turning a blind eye to some fairly obvious issues. If fans really care about Matt, they should want him to get healthy before he becomes another sad statistic."