If you’re interested in checking out what the new ads look and behave like, check out these examples from Aaron Zamost at Google:
And here’s some additional commentary from Aaron:
YouTube InVideo Ads details:
– YouTube InVideo Ads are animated overlays which appear at the bottom 20% of a video shortly after launching. If interested, users can engage in a deeper interactive experience by clicking on the overlay. This experience can consist of a video advertisement or Flash interactive takeover. The original video is temporarily paused and the user can always restart play by closing the ad. Note that if a user does not take action on the overlay, the ad will close.
– The ads are presented within partner content and targeted by channel: genre, demographic, geography and time of the day.
– YouTube will not place advertisements on all YouTube videos. YouTube is only placing ads on content from select partners.
More at the YouTube blog too.