On the catalog page, you can add a Featured Category block to appear at the top of the catalog. The Featured Category will show the featured category slider images for the first 12 videos in the category you select. If you don't have 12 videos in this category, the featured category slider will show the featured category slider images for the videos currently in that selected category (up to 12).
If you don't have featured category slider images set for your videos (located on the Appearance tab of each video), visitors will see the first frame of the video.
Navigate to the Customization tab and click Customize > Common Pages Customization. Scroll down to the Featured Category section and you can set the category you want to feature.