Here is the file I used in the latest video. It is a "cleaned-up" version of the file I'm using. I have removed some of the more experimental bits to lessen the confusion a bit, I know by experience that looking at a WM file you haven't created yourself is daunting. Even opening a WM-file you created yourself is daunting, if you haven't worked on it for a little while.
You can grab the file here: https://www.dropbox.com/s/ydb5p5b5xuu0uq1/Presentation%20-%20Elevation%20and%20Rivers.tmd?dl=0
You will need a veresion of GeoGlyph to use this file, and you can use the Community version of GeoGlyph (that is free): http://quadspinner.com/GeoGlyph#editions
Special thanks to Quadspinner for the ReFlow macro that is part of the GeoGlyph 2 addon for world Machine. You can find out more here: http://quadspinner.com.
Just to be open about it, Quadspinner is a backer of this Patreon. But this is not a sponsored link. I payed full price for GeoGlyph, and use it on a daily basis to improve my work.
Good luck with your Islands!