What you are seeing in that video is the "Magic Wand" command (keyboard shortcut: Spacebar) To use this command, all you have to do is:
- Click on the beam tool to activate that tool
- Press the spacebar over the walls, and once you see the "ghost" beam appear you can click again to have the beam modeled.
Note that it will not do absolutely EVERY wall at the same time, if you just have a closed box like in the video it will work, but for more complex things you may have to do this several times in different locations, to cover every single wall. It works best when the wall "reference lines" are cleaned up correctly.
Also, the magic wand works on most elements, so as a best practice try isolating the wall layers so that you don't accidentally "magicwand" the beams to a slab or any other elements on the screen. To isolate layers try using the "Quick Layers Palette"
iMac - MacOs Big Sur 11.6.6
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