It can happen that a PKGBUILD is no longer working. There are many variables that can go wrong. 

First you go to the AUR Arch Linux website and see if something posted a fix.

IF not you can flag the package out of date or try to fix it yourself.

We are going to analyze why it is not working.

The link we used in the video can be found here on pastebin. By the time you read this article the content of the PKGBUILD is old and unusable.