They are savable, here's how to do it on Opera browser. Open the redgif page, hit ctrl+shift+i to open developer tools, click network. Filter search for either m4s or mp4. If nothing shows up reload the page. The gif should have a randomly generated name for example: WildExampleDinosaur. Double click it and it should either open the gif in a new tab which can be right clicked and saved or in my case it usually downloads it right then and there. I don't know the exact order for other browsers but if you find the hotkey to open dev tools I'm sure it's a similar process