I worked out the percents - Pete, you let me beat you to it. What is the world coming to :-)
I got off to a slow start this morning. Temperatures in the Dallas area dropped from about 80 degrees yesterday to 30 degrees this morning and I had to bring in my potted basil and thyme plants to salvage them. It also took me multiple viewings of the video to see exactly what Blumenthal was doing with the dough.
I believe you made an error in the amount of flour. Also, you did not account for the preferment in the total formula. The preferment represents about 1/3 of the basic dough as made in the video. If my math was correct, I get the following total formula after adding in the preferment and doing the conversions of volumes to grams:
100%, Flour (350 g. + 116.7 g. = 466.67 g.)
55.7%, Water (195 g. + 65 g. = 260 g.)
1%, Malt (1/2 t. + 0.17 t. = 0.67 t. = 4.69 g.)
1.59%, Salt (1 t. + 1/3 t. = 1.33 t. = 7.42 g.)
2%, Yeast (7 g. + 2.33 g. = 9.33 g.)
Total dough weight = 748.11 g.
Dough ball weight = 150 g.
Number of dough balls = 748.11/150 = 5
I assumed that the malt syrup is non-diastatic (because of the short fermentation times), that the salt used is regular table salt (not Kosher), and that the yeast is instant dry yeast (because it was not re-hydrated in water).
Actually, I think Blumenthal did a creditable job with the dough preparation. I am talking here onlly about his technique, not whether his dough captures the authentic Neapolitan experience. He uses a preferment that is similar to the dough into which it is to be incorporated, which ensures the same hydration in the final dough, and he uses an autolyse-like process by adding the salt and yeast after the rest period. What Blumenthal does not say is whether the preferment was allowed to sit at room temperature for about a day or whether it was kept in the refrigerator. At 2% yeast, which is very high and more characteristic of so-called "emergency" types of doughs, the preferment would be extremely active and rise very quickly at room temperature. In breadmaking circles, such a preferment would normally be kept in the refrigerator, either immediately after making or after a short room temperature rise.
I agree with you that 2 minutes total bake time is most likely too little if a standard home-type oven was used.