As you can only "use" vaapi via vlc expect the mplayer numbers pointless as they do not show a correct picture. vlc needs much higher cpu especially when you switch from xv to opengl (together with amdcccle set to quality), the cpu usage is very high then. It would be certainly more efficiant to use other players which is not possible. Then xv would work as expected it would be a major step forward, but that was never the case since the dedicated overlay parts got removed from the chip. But who is really expecting xv to work with fglrx? A cheap ati hd 5 card is completely useless, even onboard ati would be better - there you can already use oss drivers, but for the new ones you need to wait 6/12 month till it will be standard in the distributions.