The most obvious meaning of the tape is that bin Laden is still alive.
Given the impact that Bin Laden has had on the recent history of the world, there is surprisingly a good deal that remains mysterious about him.
There's overwhelming evidence bin Laden was behind the attacks of September 11. If the family chooses not to believe that, that's just how families operate.
After all, the chain of custody of these tapes is the one way to find bin Laden. He obviously feels secure enough that he can release a number of these tapes.