It sound like the tutorial is saying (a video link with a time stamp)
that's tricky to show you once it's all up
Does that mean the audience (such as me) would think the approach is tricky when it's all up?
what does it's all up mean in this context (use panels to soundproof a room)
"It's all up means once all the panelling (it) is all installed / mounted (up on the walls).
When he says "that's tricky to show you once it's all up", while pointing at part of the panel interlocking mechanism, he means the part he is pointing at is difficult to film / see once all the panels are assembled. It is not a comment on the difficulty of the approach or process of assembly.
