It's the Alphabet by Danv500 a classic, nostalgic user-uploaded alphabet video on YouTube originally published around the mid-2000s that gained hundreds of thousands of views as an early internet-era learning clip for kids. The letters were made out of weird shapes, objects and creatures followed by stick figures.
Danv500 LINK--> https://www.youtube.com/watch?v=drj8BGLL6lE
