Send a 2 minute video recording of yourself answering the question "Why do you want to be a student ambassador". Then had to attend afternoon of training covering campus tours, course information and university information (all the things visitors and prospective students may ask).
Had to record a video in which you explained the questions they provided for you. Mostly talking about how you fit the role, why you like your course and what you will do.
I applied online. The process took 5 days. I interviewed at Bournemouth University (Bournemouth, England) in Sept 2015
Interview
I submitted the online application and then was waiting for about 5 working days to get the email of invitation to the assessment day. After that, I got the offer.