Glyph uses MoviePy to transform videos into looping GIFs. MoviePy has some dependencies that can’t be installed with pip, but it does what it can with what’s on your computer when you’re using it. I find that GIFs made with Glyph look best when they’re processed by MoviePy with help from an image manipulation program called ImageMagick. Go ahead and just install ImageMagick unless you have some reason why you really don’t want to. Install here.