If the installation is similar to the one of the Faital speakers I listed 5 posts above, removing the whole dash is not needed. All that was required was removing some trim pieces.
The issue might be the clearance between the windshield and the dash. The Faitals cleared pretty easily, but they have a small neodymium magnet assembly. If these speakers have a large ceramic magnet, that could present some clearance problems for installing with the dash in place.
@Light Harmonic, this is the exact reason everyone is asking. If your speakers are bigger in dimension they might not be swappable without removing the dash. Seems people have successfully swapped out Infinitys and Faitals without full dash removal. Your DIY video doesn't show the view of the magnets for any driver so really hard to tell. I think the answer to this question is important as a decision factor for many potential purchasers. In addition, it would be hugely beneficial to show a step-by-step full dash removal if that is in fact required.