Try converting that to MP4 video if you can, or just try to reduce the file size. I think there is a size limitation on videos, though the listing page doesn't currently state that. I want to say it's either 10MB or 20MB, either of which you would be over if so. That doesn't explain the error message you're getting, but I'm suspecting it's just giving you the wrong error message.
Or there's just another eBay glitch and you'll have to wait until it's resolved, who knows!