Technicians are in charge of setting up the video, audio and staging for events. Usually most of their work is done prior to the day of the event then they are only present day of in case something goes wrong.
They also take small PA systems to various events throughout the campus. For example, if a speaker is coming to speak to a fairly large crowd, they can call the O'Connell Center and get a small PA brought over so the audience can hear the speaker.
The audio below (2:50) is an interview with Oscar Bode explaining what Technicians do for events: