By checking out the video description, you'll come across a link that leads to
Upon visiting the provided link and locating your desired project, simply right click on the page and select "inspect element" if you're using Safari or Google Chrome. This will reveal the necessary javascript code for building the application, allowing you to download the minified version of three.js for inclusion in your project. Alternatively, you can access the source code by clicking this link:
https://github.com/mrdoob/three.js/
We hope you find this information useful.