From MP3 Toolkit:
Video Rotator is a Windows application for rotating video clips 90 degree clockwise, anticlockwise, horizontal mirror or upside-down. Video Rotator supports most popular video input formats such as AVI, MPG, FLV, MP4, WMV, MOV and 3GP etc. Video Rotator also allows users to save the rotated videos to 5 popular video formats: MP4, MOV, FLV, AVI and MPG. Further more, Video Rotator supports iPhone / iTouch MOV format and Smart Phone MPEG4 format. The program supports batch mode so that users are able to rotate & flip videos in bulk.