Unless your particular UA was marked to be "observed"....that doctor over-stepped his boundaries, if the UA is just a pre-employment deal, and we aren't talking National Security, there should never be anyone "watching" you urinate.....kinda sounds like a pervert to me!
I have worked the last 16 years as a licensed nurse and have had to deal with more than my share of UA's. My best advice is to carry in clean urine. Make sure to have over 40ccs. Its a damn shame they dont have a piss test for "stupid". Drugs don't ruin careers.....drug testing does!.....Good Luck!!