dslrBooth allows you to see a video preview during the countdown before the photo is taken.
During testing of this feature, a watermark will be displayed that can only be removed by purchasing a subscription. You can do so here: https://dslrbooth.com/pricing.
You also have the option of not using this feature altogether by turning off the Show Live View button under Settings, Screen Editor, Welcome Screen.
Live View Watermark
Updated this week