Forgot to mention: hanime.tv most likely isn't doable since the videos on there are very large and are high-quality files. The way their website works is they gradually stream the video to you, like YouTube, instead of downloading it all at once (which is what Zenith Grabber does).
ok hear me out, i managed to get the direct link to a hanime.tv video. (https://m3u8s.highwinds-cdn.com/api/v9/m3u8s/rmwdb296gb7vwt4nyxjnkzyqf2Ztf0lzAt8...)
if you somehow can get the links in your program then this "streaming" shit should work. (hanime.tv tags and booru website tags aren't the same, that would be a problem)