What this video covers
The clip is about concrete, which people assume is immune because it is not organic.
Concrete is porous. Growth roots into the surface much as it does on drywall, feeding on dust and organic residue held in the pores rather than on the concrete itself.
The takeaway
Do not assume a hard surface is a safe one. Garage floors and basement slabs need the same moisture control as any other material.
Read the full written guide: Mold on Concrete.