If you ran a successful awareness campaign using a 30-second video ad and now see the value of remarketing to audiences who watched it with memorable, shorter video ads, what video ad format should you use to achieve that goal?

To achieve your goal of remarketing to audiences who watched your 30-second video ad, you should use YouTube's Bumper ads. Bumper ads are short, memorable, and non-skippable video ads of up to 6 seconds that run before, during, or after other videos on YouTube. They are designed to increase brand awareness and reach, making them ideal for remarketing purposes.

Here are the steps to create a Bumper ad:

1. Sign in to your Google Ads account.
2. In the page menu on the left, click Campaigns.
3. Click the plus button, then select New campaign.
4. For the goal of your campaign, select Brand awareness and reach.
5. For the campaign type, select Video.
6. Click Continue.
7. For the "Bidding strategy," select a strategy from the drop-down menu.
8. Fill out the rest of your campaign settings and click Next.
9. In the "Ad group type" section, select Bumper.
10. Fill out the rest of your ad group settings.
11. Under "Your YouTube video," paste the URL of the video you want to use for your ad.
12. Click Save and continue.

Remember, Bumper ads are best used to reach audiences with short, memorable messages, so it's important to keep your content engaging and to the point.