Game clips and screen recordings are large, and Discord refuses files over its free upload limit. This is a short workflow that gets a clip from your recorder to a channel without a failed upload.
The limit itself, and the date it was last checked, are stated on the Discord compressor page. Discord has changed it more than once, so that page is the number to trust.
1. Record only what you need
Size grows with length. A ten second clip of the moment is far easier to fit than ten minutes with the moment somewhere inside it. Save the full recording if you want it, but make the clip the part people will watch.
2. Trim before you compress
Cut the start and end in whatever editor or recorder you already use. Every second you remove is a second the compressor does not have to fit into the limit.
3. Compress with the Discord target
Open the Discord compressor, keep the Discord target selected, and choose your clip. It runs in your browser, so the clip is not uploaded anywhere.
The target aims below the Discord limit with some room to spare. A megabyte here means 1,000,000 bytes, the same way Discord counts.
4. Check the size and the picture
The tool reports the before and after sizes and whether the result came in under the target. Play the result. Fast motion and small text lose detail first, so check those parts.
If the tool says the clip cannot fit at a watchable quality, it is too long for the limit. Go back to step 2 and trim more.
5. Post it
Drag the compressed file into the channel. If Discord still refuses it, confirm the current limit on Discord's own support page, since that is where changes are announced.
Clips for other places
The same steps work for email. See how to send a video that is too big for the general case, or use the email compressor directly.