In this quick video I wanted to demonstrate the low-light ability of the 7D vs the 5D Mark II. 3 Light bulbs above the pool table, set to half brightness.
Both cameras were set to record at 30fps, 1/60th second shutter, f/4.0, and ISO 1600. Both cameras were initially manually focused on the yellow 1 ball.
Update: I forget to mention and this is important (sorry). The EOS 5D Mark II was shot using the Canon EF50mm f/1.8 - set to f/4.0, while the EOS 7D was shot using the EF 24-105mm f/4L - set to f/4.0. Despite, the lower quality lens on the 5D Mark II it's video actually looks a tad bit sharper - though very close.