AUM or OM? Which one do you use and why? (2 minutes)

I just received a GREAT question and felt that it's worth responding on a short video:
"There are two different versions of pronouncing 'Om' - 'Aum' as per vedic sanskrit and 'Om' as per classic sanskrit. In lessons, I believe you use 'aum'. Is there a reason you prefer one over the other?"
If you have any questions about yoga, let me know.