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.
I was promoted as "Free," but in reality it will only allow you to process 15 seconds of video without buying a license. Furthermore, I'm suspicious that down came with lots of unwanted baggage that I had to work hard to remove. I don't recall whether it introduced lots of pop-ups in my browser, or because it was launching unwanted applications. I do recall that almost immediately after installing, I decided it was too dangerous to leave on my machine, and I took actions to remove it and the things that seemed to come with it.
I'd avoid it. Instead, I'd suggest trying that at: http://movierotator.com/. I've been using it on another machine for several years with good results. The only problem with "Movie Rotator" is when the pixel width of the original is greater than the pixel height of your screen, access is hidden to the control buttons at the bottom of the screen.