Vid - Handbuilding a bicycle frame

[m_c]

Now if he'd "measured" both ends that would be more obvious to the uninitiated. Wouldn't he would be able to feel the difference, after all he's skilled in this work right?.

Possibly, but you've got to remember the vid is more an artists view of the craft, rather than an accurate engineering documentary!

Also, depending on the tubeset, there may not be that much difference in the butting thicknesses.