Mudder - This link should explain a bit about those types of ads:
Microsoft Advertising: Advertising Info
They'll generally be customized for you based on your past internet activity. For example, I buy car parts online occasionally from Advance Auto Parts. All it takes is for me to go browse their web site for a while then ads for them start appearing here and there as I go to other web sites......including TOTV.
Now.....back to the topic of Dr. Desai!
Bill