As I mentioned in a previous post, I hate video ads and they desperately need some standards (in lieu of common sense I guess). Apparently Rebecca Lieb at Clickz agrees. She also points out the inherent issue with pre-roll video ads, which is that A) people in offices really don't want to have their PC speakers flooding the area with Viagra ads and B) people with audio turned off or their headphones plugged in and not on their heads aren't going to hear the audio anyway.
Video ads are a stupid practice and should probably just be stopped. I don't see the value to the advertiser or the host.