This is great! He's right - there are so many vids out there claiming to enlighten you about sharpening blades, but so few of them are anything but confusing.
He's also trés entertaining, this French bloke.
I haven't tried this whetstone approach - but I have had very good results just using a single triangular stick from a Spyderco sharpmaker set. Two strokes at ca. 15 degrees and voila!