overlay and vmr

[[CrusaderSean]]

i'm curious as to what overlay 1, overlay2, and vmr9 are. are they just ways to render video? if so whats different?

from my experience, overlay 1 and 2 don't seem to be that different.
i think default in windows is vmr7 and vmr9 is available in bsplayer. is that rendering through software or something? i think overlay is rendering directly without intervention of video card. well if someone can explain this stuff or post a link i'd appreciate it.

i wonder if getting a new video card will help playing (most likely not). i think playing media files depends on cpu mostly, video card probably plays a very minor role.