What this video covers
The clip gives a threshold for deciding whether to handle it yourself.
The rule of thumb is ten square feet. Below that, with no structural involvement, it is reasonable as a DIY job. Above it, or where the structure is affected, containment becomes the deciding factor.
The takeaway
Area is only half the test. Ten square feet on tile is a different job from ten square feet on a structural wall, so material matters as much as size.
Read the full written guide: DIY Mold Test vs Professional.