Coestar narrates his Minecraft adventures for fans who watch him play for entertainment or to pick up tips, sprinkling in some language that might not be suitable for younger followers.
And that's enough for Mitchell Brown and Scotty Vrablik, American students in the Hong Kong equivalent of Form One, to reject that video from their own fledgling Minecraft website.
A growing number of teachers have embraced Minecraft as an educational tool, but are looking for "clean" versions.
" Minecraft is a totally, open-ended sandbox," which makes it easy to customise for use in the classroom, says Joel Levin, co-founder of TeacherGaming. His company created MinecraftEdu, a modified version of the game for classroom use.
Minecraft not only engages students, he says, but encourages skills such as resilience, problem-solving and thinking outside the box.