The concept discussed in the video for calculated values relies on the stock Cost and Length parameters, Cost x Length. The assumption is that the price entered for Cost is the cost of the duct per linear foot (easily applied to metric values). None of this presumes it's the appropriate way to price them, the concepts can be applied to anything else.
The other concept demonstrated in the video is adding a group header to several columns in the schedule. The trick to getting a group header is how you go about selecting the columns. When you click in a header field Revit thinks you want to edit the value. You need to click and drag to select the other columns so you don't just select the column header you click on first...click and drag...then let go of the mouse button to finish. Watching the video is probably more "obvious". Not hard to do, just subtle. Kind of like learning to drive a manual transmission.