How can I rotate a video?

If you are asking for rotate a video 90º or 180º, you should use avidemux.

sudo apt-get update
sudo apt-get install avidemux

1. open the video in avidemux
2. select a new video format and don't choose copy
3. Under "Video" click on Filters
   1. Choose "Transform" and scroll down until you see rotate.
   2. Add it
   3. select the right angle
   4. select preview
   5. ok.
4. Go to file
5. save
6. save video

And you're done.