When I have a frame with a video/gif in it, the frame just does not play anything. I installed VLC on my Mac, and that fixed the no VLC bug, but now it is just a black frame.

🗃️ I NEED YOUR LOGS TO DIAGNOSE

Your latest.log file is placed in your .minecraft/logs folder (instance folder), pickup the file and upload it into any website below.
If your game crashes please also append the crash report in the .minecraft/crash-report folder.
Paste it here so i can help you more easier

🖥️ PASTE PAGES

• Github (100MB): https://gist.github.com/
• MCLogs (10MB): https://mclo.gs/
• PasteGG (15MB): https://paste.gg/
• PasteEE (1MB): https://paste.ee/
• HasteBin (400kB): https://hastebin.com/
• CentOS (1MB): https://paste.centos.org/

Ok it works sometimes, but then it just freezes the video after playing it once.

I am able to play short videos and some 5 minute videos, but like a 20 minute video will not load. It loads on my Windows PC, but not on the Mac. It might be a CPU issue, but correct me if I am wrong.
LOGS

Oh also I don't crash, I just left after getting the logs.

Mac carries a lot of minor issues that are out of my hands, video loading is one of them.
Is planned a option to prevent that but not a specific fix. So my suggestion is use windows to get the full experience
(again, i can't fix it, because is a problem of MacOS/VLC and not directly of WATERMeDIA)