I've updated
the "mini-tut" so that hopefully it is a little more clear.
Basically, steps 1 through 3 aren't absolutely necessary. Steps 4 through 8 describe using the Grid filter and Rotation Tool to render diagonal stripes -- the only thing atypical about this is that they are rendered on the Quickmask channel (to produce a selection, and ultimately a path).
Since the rotated diagonal strips selection has its corners missing, we need to select a rectangular region that is completely covered by the strips. Steps 9 and 10 (in addition to steps 1-3) use the original text region that was previously warped. If you just used the Rectangle Select Tool to reduce the size of the selection (holding down SHIFT+CTRL while making a rectangular selection within the stripes selection), this would still work to produce warped stripes. However, if the rectangle is a different size than the original text region then the warped stripes would be a different size (relative to the size of the original warped text). If the aspect ratio (width:height) is different from the aspect ratio of the original text region then the angle and width of the warped stripes (relative to the original warped text) would be different.
By making the size of the original stripes rectangle the same as the size of the rectangle of the original text, the result of warping the stripes will match the result of warping the text*. This is probably not that important in most cases.
* If the accuracy of my warping algorithm was more precise, the stripes selection (after step 8) could just be intersected with the original text layer ("Layer->Transparency->Intersect With Selection"), and the resulting path warped to produce a perfect overlay. However, the warping produced by the script is not precise enough to rely on this.
@ Oregonian, I was a Seattle-ite about a decade ago.