That looks normal, I have that sample and it's 1444 frames / 60Hz = 24 seconds.

You can't really turn off vsync for vdpau and mplayer doesn't do gl interop.

Cpu times can mislead if cpufreq on_demand is in use as you don't know what
freq the cores are in.

UVD/powerplay is tuned for playback (at least on recent GPUs) if using with eg.
ffmpeg you can get more perf by forcing GPU clocks to high.