Google's video ads can be an interesting way to drive more traffic to your site. But if you expect video ads to be approved immediately or as quickly as your text ads, don't bank on it.
A Google AdWords Group thread has one advertiser who posted his video yesterday and got impatient. He then asked how long it will take for approval and AdWordsPro Sarah said it takes about 48 hours but can take longer depending on the "volume of submissions."
This answer really does not correspond to the answer at the FAQ, where Google wrote:
Your video ad will begin running as soon as it is processed and passes through our editorial review. This process usually takes a few hours, but it may take as long as a day.
I guess Sarah is right?
Forum discussion at Google AdWords Group.