I think there is much misunderstanding in this regards.
On the DVD or HDTV the data are stored in 4:2:0 (360x240 for NTSC). So somewhere in the chain it has to be converted to 4:4:4 (chroma upsampling) and then to RGB to output it to the display.
YV12 is a 4:2:0 format, so the data goes untouched to the overlay or VMR9 (or other filters behind the decoder). The chroma upsampling is done in the hardware of your graphics card. The overlay of the Radeon does a very good job here, but only for film material (for video material you get the inverse CUE). The CPU usage is also lower.
YUY2 is a 4:2:2 format which means vertically it has been interpolated already. Horizontally it is untouched.
This is good for video material, because the overlay doesn't know the source and always performs progressive upsampling. With YUY2 you can bypass this circumstance.
Sadly most decoders does very bad upsampling for progressive streams. They only double the lines instead of interpolating which leads to chroma aliasing.
So YV12 does NOT contain less information then YUY2, because the source doesn't have more. It is just a question of where the upsampling happens. The same applies to YUV->RGB conversion.
