A better way to do this video would have been to plot a dummy plan using all these different chart types, from destination A to destination B. Try using props a lot, there is a lotta talk in this videos but no corresponding visual aids. Frank feedback, good channel, but needs improvement in the quality for delivery of info.
Just see it as a GPS navigation. When planning the trip, you zoom out as much as you can (pilot chart and navigation chart). Then, when you get closer to your destination, you zoom in more and more (approach and harbor charts).
They've only been a teaching tool in these last 4 or so decades. They were used with pilot charts to get the least distance track or great circle track across an ocean. The projection unlike Mercator where a straight line from point A to point B can be used to measure the bearing between them but not the distance. A straight line between points shows the actual shortest distance but the bearing changes so waypoints where taken along this line to get the waypoints to plot on a pilot chart. The popular routes are already plotted on the pilot charts these days. But to understanding great circles they are the best aid to the navigator learning about this type of sailing
