I tried posting this [ url=https://imgur.com/4KapD7b.gifv][ img]https://imgur.com/4KapD7b][/img][/url] (ignore the spaces, of course) in another post but the image broke. Is the format wrong? Is the image too big?

The below format should show it correctly.

the image name: https://imgur.com/4KapD7b needs to end with .gif or .jpg or .png

So check your address and find the link with that ending, that's what you'll need. I don't use imgur, but I've heard there are proper links somewhere in the page.

] in between the img tags you have https://imgur.com/4KapD7b , it's missing .gifv (but that doesn't work on subeta i think, so in general i'd use .gif instead) should be

but in this case i would just link to it. it's too big for the forums (700 px wide, 400 px tall)

"Do NOT post images or URLs that exceed the current limit of 325 pixels in height or 450 pixels in width. Animations must be no larger than 5MB. Any content found to be in violation of this rule will be cleared or edited by a member of staff.

If you wish to post a large image or URL which exceeds these limits, you must link to it using sCode."

Thanks, everyone :D