There are a couple of ads appearing on Fire TV devices right now that will reward you with Prime Video credit for watching a short video ad. The first is a blue banner ad for an Oral-B toothbrush that may appear on the Fire TV home screen. Selecting it and watching the associated video ad will earn you $3 in Prime Video credit. The second ad to look out for is for Shell Gasoline which appears while the Fire TV screensaver is going. Interacting with the Shell ad and watching the associated video will earn you $5 in Prime Video credit. Both of these ads are targeted, meaning they will not appear on all Fire TVs. Keep an eye out for them to earn some free credit in exchange for a couple of minutes of your attention.