I found it on the internet.
Credit to AumSum for that sound effect. Video name: Digestive System In Humans, but with the extended cut, someone else uploaded it with the extended cut, as the beginning scene was cut from the original video, and that beginning scene is the extended cut. Video link to see extended cut: https://www.youtube.com/watch?v=f1r6FI-iv3M&t=18s. Video link to see the original AumSum video: https://www.youtube.com/watch?v=bFczvJp0bpU. Note: In some outros of old Aumsum videos from 2014, you may see a clip from the extended cut of the original video, this proves that the scene was cut much later.
