This feature is going to be released in a few days, need some time for testing. the whole process takes less than 15sec xD. zip' to get a easy to share format that can be uploaded in DeviantArt(?). once wallpaper is added to Library you can right click and select 'Export Lively. What I ended up doing is before setting the wallpaper I play the video/webpage/application in a small window and then screencapturing that region & converting it into animated gif (did I just make a screen recording tool now lol). This took some work, Initially I tried using ffmpeg to generate the gif but that would only work with video wallpaper files. into Lively window both the image & animated gif will be created by lively for you. My objective with Lively is to make it as simple as possible, so I automated the full process.when you drop files/webpages/application. One of the complaint/feedback I got from reddit is it was too difficult to add wallpapers in Library as it requires a thumbnail image & animated gif to show preview of the wallpaper.

Lively wallpaper library