There is a box with each video item called "Hub Page Teaser" - same box that's used for the Webinars. This is where you can put text like this. The image used on the Hub Page come from the Image field, and serves as a screenshot of your video. These images can be uploaded as any size, but will be scaled and cropped to 600x340 for uniformity - or you can make sure the image is created at that size from the start.