What this video covers
The clip covers the bleach question and the material distinction behind it.
On non-porous surfaces like tile and glass, where the colony sits entirely on top, bleach works. On porous materials the water carries into the substrate while the active ingredient largely does not, so the roots survive.
The takeaway
Bleach is a surface product for surface problems. Reaching for it on drywall, wood or grout removes the colour and leaves the growth.
Read the full written guide: Does Bleach Kill Mold?.