Sunshine is not really geared towards selling videos but there is a workaround with a small known feature of the Digital Downloads add-on. Sunshine galleries only display .jpg image files. However, you can upload any type of file to the gallery. The Digital Downloads add-on will actually include any file that matches the root file name with a different extension.
For example, if you upload “image1.jpg”, “image1.png”, “image1.pdf” and “image1.zip”, all 4 of these files will be included in the digital download.
Currently allowed extensions: .zip, .tif, .tiff, .dng, .png, .raw, .psd, .pdf. You can add more extensions using the “sunshine_allowed_file_extensions” filter.
Upload an image with any filename, let’s use “video1.jpg” as an example. A screenshot from the video might work well here.
Create a zip file from your video, name it “video1.zip”.
Upload it into the Gallery upload area just like you did the image.