I just bought my son a new OTG for his B-day yesterday, and noticed Weber has added a lid therm. Similar location as that gent's but not that close to the grate, more inline with the vent. I don't think it matters for grilling, but for smoking his might be a better location.
Tim
I don't have any pics handy but I bought a weber replacement thermometer and drilled out he center rivet from the vent on the lid of my 22 OTG. After drilling out the rivet I placed the therm through the hole I drilled and tightened the nut on the opposite side. Has been working like a charm for a few years now.