First, I'd like to say I love my Slingbox HD-PRO. I constantly show it off on my android and love watching TV outside on my laptop with my cigar and cognac. That being said, it appears to me someone has decided to make finding the slingplayer software download ridiculously hard to find. Eventually, I did find it, but I just had to vent.
The stand alone player program has basically been replaced by the web browser setup. Sling Media is no longer updating the stand alone player. The Place Shifting Enthusiasts site does maintain an easy list of Sling Media downloads that makes it easy to find older software hosted on Sling's sites for those that want to use the optional players.