if Allah Almighty has said that He can forgive any sin (except associating others with Him) provided there is a genuine intent to seek forgiveness, so who are we to judge people then? MJ might have gone through different/difficult phases during the course of his life (and infact we all do), but who knows except Allah, maybe he had asked for forgiveness?
I ask who are we to judge people on any basis? do we carry a clean slate to start with? No i dont think so..
I had heard rumours about him being reverting to Islam, but his brother's speech in the video which you've provided clearly confirms that he indeed had embraced Islam. What if he was a better muslim afterwards than most of us here? who knows?