i have had this experience..and thank god it was a good one!!
well, they will probably start with you,, your SOP, your acadenic and personal goals,, a question which will be very common will be that where u want to see yourself in say next 5 years..and how you plan to reach there..
why u think we should choose u
abt your resume/work experienece
what will u bring in the class
abt the field you have choosen..
basically they will test your communication skills and how you handle yourself while talking to senior faculty and all..
nutshell, just a brief abt yourself, your chosen field in MPH, ur past experience, goals and all..
good luck and do tell us how it goes,,,,