My browser also fails to open them, unless I make the following change:

NSFW WARNING!

Original link example: https://api.redgifs.com/v2/gifs/mediumaquamarinecharmingtahr/files/MediumaquamarineCharmingTahr-silent.mp4

Becomes: https://redgifs.com/ifr/mediumaquamarinecharmingtahr/

(Please forgive including NSFW link to demonstrate link modification)

There are 3 changes to the link: remove api, replace first two subdirectories with ifr, and remove last two items

Wanted to share in case anyone else has the same difficulty

It's the app, the same thing happened to sync a while back

{"error":{"code":"FileAccessDenied","message":"Access to this file was denied for your application.","status":403,"rtfm":"https://github.com/Redgifs/api/wiki/Embedding-gifs#file-access"},"docs":"https://github.com/Redgifs/api/wiki/Embedding-gifs#file-access"}

Just checking you’re not in a state that passed one of those draconian porn verification laws? Redgifs is following suit with whichever states PornHub is blocking. Try launching the lemmy page in your browser directly and see what you get too.