Well,
I have a scene with a LARGE crowd of different types of aliens. What I ended up doing is animating about 10 avatars in a straight line then exporting the video and the alpha channel, then using it as a transparency on the floor prop. I exported them at 720P uncompressed. Then I brought them all into one scene and set up about 60 720P videos with transparencies. Now, I quite understand the large number of RAM going into this considering the 720P uncompressed video with transparency, and it makes sense. I just though you may get a kick out of how much ram it was used for one shot. It actually went up to 24GBs. Thank God for 32GBs of ram and 64bit :)
There may have been better ways of doing it (with multiple larger groups, as opposed to 60) but I was only able to achieve desired results this way.
Alienware 15, i7 4710hq, GTX 970m, 16gb ram, 4k display, 1.5TB SSD raid.