The x264 benchmark measures how fast your machine can encode a short, DVD quality MPEG-2 video clip into a high-quality x264 video clip.
It will give you results in FPS that can be used to compare the performance of different CPUs and different CPU settings.
"What's x264, you ask? It's more or less the next-generation Xvid/DivX codec. I think it's ideal for a benchmark because the application (x264.exe) reports fairly accurate compression results (in frames per second) for each pass of the video encoding process, and it uses multi-core processors very efficiently."