Can't you vacuum a passive system to make it much safer? This would end the explosive mixture and fumes when opening column issues. I know the Mr Extractor can't do this but any properly designed unit will.
Absolutely and bingo! GO gets the big cigar!
First vacuuming out the system would indeed solve the problem, and it would be that simple to solve if the Mr Extractor were equipped with that simple valve and fitting.
Like all reputable passive extraction system's have employed since long before the Mr Extractor was presented as a new innovation and the safest system.
PS: That is a separate issue from publishing a video viewed by the public and promoted as the safest, operated inside. If the safest doesn't at the very least, start with observing that very basic Number 1 rule, what must the public and folks writing legislation think?