What macsak said is true. The student panel is worth very little in the interview process. I think the students will give their opinion, but that’s about it. Unless you say something really offensive I wouldn’t worry about it. As for those who monopolize the conversation, remember, they have a bigger chance of saying something stupid and remembered for it.
OU has a point system. You take the AA and the TS scores, the overall GPA, the SGPA X 1.5, the score for the interviews, experience, service, and anything else they give point value for, add it all together, and form a list. The top 10% get automatically accepted without discussion. The other 90% they discuss the pro’s and con’s. This is when your interviewers defend or hang you.