Discord recently implemented "temporary" CDN links to combat file hosting abuse. If you have the ID but the video won't load, the link may have expired, or the original message containing the file might have been deleted by the user or a moderator.
Because Discord's CDN is public, anyone with the direct link can view or download the file, even if they aren't in the original server where it was posted. Experts at AVG warn that while the MP4 format itself is generally safe, users should be cautious.
When you upload a video, Discord assigns it an ID like 859233066174345217 . This ID allows the platform to retrieve that specific file from its servers regardless of how many other files have the same name (e.g., "video.mp4"). How the Link Works
The folder where user-uploaded files are stored.
Typically, these IDs appear in Discord CDN URLs, which look like this: https://discordapp.com[ChannelID]/859233066174345217/video.mp4