Confused about proper operations after watching video

[Boeing or not going 578]

I just watched this great video

 

http://www.flightvideoproductions.com/pilatus.htm

 

But am now confused about proper operation of the PC-12

 

I've read others say the oxygen switch stays off unless in an emergency, but in this video it is on.

 

In the video the pilot doesn't press arm for the vertical speed mode control, he presses engage.

 

Who is correct?

[aeronauta 66]

It looks as if he is flying at 15000ft so oxigen required (The before start says OXIGEN ON),  ,he may be using IAS hence ENG...but could not see it 

 

Jorge

[CaptKornDog 281]

Checklist says oxygen on before starting engine and oxygen off after shutdown.