1. Any video can be compressed.
2. That's not how you compress video.
Why don't some files compress very much? - WinZip - Knowledgebase
This link above has information on why your video isn't compressing the way you think it is because its a completely different function.
You're looking at a different kind of compressing which entails reducing the quality of the video in various kinds of ways for the best picture with the least amount of space. There are many tools to do that.
Here is an example tutorial.
https://blogs.it.ox.ac.uk/adamweblea...ing-handbrake/