If you submit as a post a super large GIF (submitting via Reddit's upload service), such as one of the ones from r/highqualitygifs, Reddit will try to do its normal thing where it generates various MP4 URL previews of the image, available in the JSON in preview.

But for these large GIFs, these MP4 URLs are all broken.

Take this post for instance [direct link to JSON], where the GIF is around 100MB and a little over 1 minute long. It links to this URL as the "source MP4 URL", which you can see doesn't exist.

For what it's worth, and if it's extra incentive, this causes both the website and the official Reddit iOS app to fail as well and just show a grey box.

This also applies to images uploaded to Imgur rather than Reddit's own service. Example post [Direct JSON]. However what happens here is that the "source MP4" loads, but none of the other previews do.

Totally understandable if you don't want to render previews for large GIFs, but would it be possible to set the URLs to null, or just not provide MP4 previews in those cases? As client-wise you see the URL and expect it to be there, but it's just a broken link and it's bizarre to loop through them until you find one that works.

[Note: I've posted in r/bugs as well but as this is related to the API I thought it would be relevant to include here as well.]