That demo is here:
@keyframers covered it much nicer than I did and made this video. (Seriously, it’s so clear and concise — it’s a great watch.)
I particularly like how quick’n’easy creating, exporting, optimizing, and integrating the actual SVG codes in their demonstration.
Their final demo:
See the Pen
SVG textPath Animation on Scroll Tutorial | Keyssentials: Web Animation Tips by @keyframers by @keyframers (@keyframers)