Here are some videos on Youtube from Fireplaceblowersonline.com that discuss differences in blowers vs blower kits, the difference between the FBK series fireplace blower kits, and demonstration of air flow from a standard replacement blower. More videos will continue to trickle in. Current videos will also be replaced with higher res better quality video.
Air Flow Demonstration
FBK-100 vs. FBK-200 vs. FBK-250 Fireplace Blower Kits
Do I need a replacement fireplace blower or a blower kit?
Air Flow Demonstration
FBK-100 vs. FBK-200 vs. FBK-250 Fireplace Blower Kits
Do I need a replacement fireplace blower or a blower kit?