In that video the top of the towers stay in one piece, Im asking will this happen in Blockland too?
Well, in the video, the tower stays in one piece because it wasn't effected by the explosion. Thing is, according to the info Kompressor gave us, if we blow the bottom of a build in Blockland, the top will simply hover and not be effects.
As previously said though, you can use events to make it so as soon as a support is blown, whatever is held up by that support will also collapse.