Let me dig it up - they sort of contradict themselves in two of their technical help topics.
One topic says that Media Manager requires 4.2 DM and 4.2 OS - while another states that Media Manager requires the two 4.2's and must be either 8100,8300 or 8800 series BB.
It could very well be that the second article was written before the 4.2.xx code was produced for the 8700 series BB.
I'm just happy it works - saves me from having the DL some shareware picture uploader that may or may not work.