I allow Google to show me its own ads, which are strongly graphically constrained compared to regular web advertising. But video ads are just insufferably obnoxious.
The worst thing about video ads is the bandwidth wasted on them. Especially in a country with not-so-good internet, those seconds wasted on video ads are precious.
It also drives me crazy when they play an ad before you can watch what is effectively an ad that you chose to watch (trailers, previews, etc.)