webvideoreport.com has a bit on this - advertising on YouTube requires a $50,000 spend within 90 days for example. Other user generated content sites like Metacafe ranges between $10 CPM to $35 CPM, Break.com placements range from $10 CPM to $35 CPM and a pre-roll video in the music section of MySpace.com (15-second video with a 300x250 pixel ad unit) carries a $25 CPM. On "Telly replacing" sites such as NoGoodTV CPMs range from $15 to $40. Meanwhile on Wall Street Journal the CPM for video on WSJ.com is a whopping $90.
What do online video ads on video sites cost?