Watching the blackbelts is also confusing because they don't actually do what they're saying to do. Some have their back hand over their opposite hip, some have bent fingers, some have the lead hand rigidly straight... one blackbelt even has his feet about 4 inches apart pointing in almost perpendicular to one another.
I unfortunately have been guilty of this myself.
My Sensei once said that when a student gets their black belt, they shouldn't be allowed to talk for ten years.
A dynamic that might be in play is that your Sensei may have changed how he performs the techniques as he works on different aspects and subtleties of the techniques, and the blackbelts might still be doing it the way they were originally taught (or what they thought they were taught). For my first three years, we did shihonage ura with a very specific wrist motion, but then Sensei changed it to a wrist position that had a very different effect on uke. Even now, ten years later, I tend to stick with the first wrist movement, it is what is more ingrained.