Genghis
Yes, Streaming means that it loads it from the drive as needed instead of loading the whole sample set into RAM.  Someone may come along with more (and more accurate) info, but off the top of my head, the ones I have that stream from disk are BFD3 and Kontakt (I think).  If I remember correctly, Superior Drummer loads into RAM, but I could be mistaken on the new one.
 
I ended up grabbing a second 1TB drive on sale and I'm finishing copying most of my main samples over to it now.  I figure that will be better than cramming Superior Drummer 3 on that partition.  Debating on moving Kontakt samples as well though.  Not sure they are as easy to navigate if you load an existing project.  BFD3 and Superior Drummer you just load them up and change the path. Easy Peazy.

Thank you for the information. 
 
I have some Kontakt instruments as well. Also Addictive Drums 2, Addictive Keys, Orange Tree Steel Strings, AAS's Strum GS-2, AIR's Hybrid 3 synth and DB-33 tone wheel organ... How did you figure out what streams and what doesn't? Would love to figure it out with my VSTi's!