I may be missing something here. Going from your screen shots, all the selected fields have the same left position (174 pixels) and are all the same width. Thus the align or resize actions you describe will have no visible effect.
What result were you expecting?
On the demo I was watching, his went all the way to the grey box - so his were longer.
Then the tab control ( the grey box ) should also be selected.
EDIT (I am not seeing that grey Tab Control box of which you speak., Thanks) 2:20PM
Weird, on his, he did not have one longer than the other, he just made it go all the way to the grey, for me, I had to use one field longer, then do it.
Also,I just realized you have to use the align before using DISTIBUTE for vertical or horizontal.
Thanks - what you said to do worked, but he did not have to do that. Weird.
If I am understanding what you meant by "the grey box", it's the object on your screen that looks like a file folder with tabs labeled "billing", "shipping", "notes"....
You shouldn't have to align fields before distributing them.
If you select a group of objects on the screen and select the align left edges button in the inspector, (Top left button in the arrange/align section of the inspector) the object with an edge furthest to the left will stay put and all the other objects will slide left until their leftmost edges align with this object's left edge. Since all your selected objects that are visible in your above screen shot already have their left edges aligned, nothing will happen if you click this button. To get a different result, you'd need to select something else on the screen. The only exception to this behavior is if one of the selected objects is locked and none of the rest are. Then the objects will align to the locked object instead of the leftmost.