See when they show the information about the game being tested.
Battlefield: Bad Company 2
Custom (Highest) Quality Settings, 1xAA / No AF, 8x MSAA / No AF, vsync off, 1680x1050 / 1920x1200 / 2560x1600, opening cinematic, 145 second sequence, FRAPS
So you would match up the settings and resolution, then go to the opening cinematic and once it starts rendering hit the Benchmark hotkey on FRAPS (after setting FRAPS to record for 145 seconds) and once it finishes you can compare it to the review's results.
i actually just figured out the console commands for steam benchmarks...
you just use record and timedemo commands to record a section of gameplay, and then it will re-run thru it and spit out your FPS statistics. and i'm sure there is a way to script it to run a few times over to get a more stable result...