The teacher stumbling at the front of the classroom in his white briefs, pants pulled down to his ankles by a student, probably wishes he were somewhere else. That place is probably not YouTube.

Captured on video, the scene has been replayed thousands of times and posted by several users on the Internet's most popular video-sharing site. It is not clear where the video was shot, but a quick search on YouTube will turn up hundreds like it.

Such clips hurt teachers, British Education Secretary Alan Johnson said.

"The online harassment of teachers is causing some to consider leaving the profession because of the defamation and humiliation they are forced to suffer," Johnson said at a national teachers' conference Tuesday.

The secretary was speaking about new government guidelines for confiscating mobile phones and other devices that are used to record malicious videos in the classroom. However, Web sites that host student-made videos must also act, he said.

"These are big companies we are talking about," Johnson said. "They have a social responsibility and moral obligation to act."

Google Inc.'s YouTube offensive videos when complaints are made, company spokeswoman Julie Supan said in an e-mail.

"Of course there is a tiny minority that uploads content which is contrary to our guidelines," Supan said in the statement. "When this happens, the YouTube community is quick to flag it, we then review the videos and where appropriate remove them."

The video of the teacher in his briefs was still available Wednesday, as were clips of a teacher walking through cellophane tape covering a classroom door and a student using ketchup to feign a head injury in class.