Great work on these videos, very proud of you. I need to spend some time to make some videos for you for the accessibility side of it to promote accessibility and Organteq 2 for blind users.. I am impressed with your description and overall flow. keep up the amazing work and thank you.
I think pre-delay is more something like the time it takes for the sound to reach the walls and come back to the listener in the form of reverb. As long as no sound has returned, you cannot hear any reverb. A short pre-delay means the reverb starts immediately (short distance to the walls) and a large pre-delay means the sound takes time to come back (large distance to the wall). This seems very different (almost opposite) from what was said in the video...