Using other potatoes

Worth a shot, but there are some potential problems- the moisture content is higher (they specifically choose low moisture potatoes), getting them to a cutting consistency would be tricky, and they might actually bleed sugar syrup-baked yams do- which could be pretty messy. For what it's worth, yams are not potatoes. Nor, for the matter of that, are they yams, which you're not likely to find outside of well stocked ethnic markets, but the term has come to be pretty consistently used for orange sweet potatoes and it's probably safe to assume that's what you mean.

Haven't tried this recipe with yams, but based on the recipe, I don't see why it would not work. You might have to watch it more closely. The sugar in the yams would make the frites burn more easily. And I'm not sure that it will crisp up like white potatoes.