The use case is pretty much the 3rd sentence in the link:

> It is helpful if you accidentally record more than 100MB (the github limit) for a demo video you wish to put in a Github PR.

In other words, you have a video, you want to attach it to the PR, it's 105MB. Now your option is to put it on YT and share a link, or use this tool and be able to simply drag/drop it to the PR.

In the demo, the 118MB file is compressed to something like 18MB, which is quite impressive, and could also help people who have slow upload speeds.