Embed the SD versions of gfycat.com links in previews to avoid the broken embeds and saving bandwidth..

If you like to share gameplay videos recorded with shadowplay using gfycat.com then you might have noticed that some of the videos/gifs won't play in discord at all.

Here is an example of one that won't play: https://gfycat.com/softmisguidedavocet it will only show the first frame of the video and that's it. Should be very easy to reproduce if you aren't aware of this bug.

If you try it in Firefox it will show the error 502 bad gateway:

Maybe this problem isn't related to the file size since this 4K video plays fine in the app: https://gfycat.com/nippymemorableelkhound

Still, maybe we don't need downscaled 4K or even 1080p videos playing in the desktop app? It's neat when it works but frustrating when it doesn't. If you all used the SD versions I bet no one would notice the difference and people would save bandwidth.