It's difficult to do an apples-to-apples comparison, because everyone sets their camera differently (i.e., flash mode, flash output, display brightness, camera power down timer, display off timer, etc.) and that can affect the duration of the battery. /QUOTE]
What I did for my comparison was put my S90 in front of the television, then shoot video clips until the battery showed low, which was about 70 minutes with either the "1000mAhr" or the "1400mAhr" China batteries, and about 112 minutes with the Canon battery that came with the camera. All batteries had been through a few charge cycles before the test, and re-test results were within a couple of percent.