A teacher in Geelong got involved in a sex video scandal, but he may still be able to keep his job.

A teacher at Oberon High School in Geelong was caught in a campus scandal that has gone viral after a graphic video of him and a student who graduated in 2008 was discovered by students online.

A preview of the video shows the couple naked and the girl blindfolded in the middle of a sex act.

AdelaideNow reported that the ex-student explained on Wednesday that everyone who knew them was aware that they were in a serious relationship. The teacher and ex-student live together and jointly own a business.

"We're consenting adults," she told the media.

Oberon High School principal Alison Murphy said she learned about the sex video on Tuesday, and the matter is under investigation.

AdelaideNow reported that in spite of the video, Ms. Murphy said the teacher was "well regarded."

Ms. Murphy said there was no evidence of a sexual relationship between the teacher and the student before she finished school. She further said it would be inappropriate to suspend the teacher until investigations were completed.

RateMyTeachers.com describes the beleaguered teacher as an intelligent man who is always willing to help students.

The Department of Education has confirmed it is investigating, and warned of the dangers of cyberspace, AdelaideNow reported.