I'm having many difficulties with the video editor. One issue is that I can't figure out how to right a video that is sideways or upside down. How can this be done in Blender?
In the properties panel N, of the Video Sequence Editor there are some setting for the active strip. Scroll down to the Filter heading and there are two check boxes to flip the strip on the X and the Y axes.
Your other option is to add a transform strip, then use that to rotate your clip.
With the clip you want to rotate selected add a new transform strip by either going to the Video Sequence Editor header Add > Effect Strip > Transform, or by pressing ShiftA.
Let me extend the answer from @David, the transformation strip rotation works but doesn't correct the aspect of the image. If you want to rotate and keep the original aspect then follow these steps. I'd love it if anyone has an easier way of doing this...
- Note the original x and y video dimension, for this example let's assume 1080 x 1920
- Add the transform strip with a rotation as per @David's answer
- In the properties for the render change the Render Dimension to swap the x and y
- In the transform bar add the scale parameters entering the formula based on your originally noted dimensions, so "1920/1080" in the first field and "1080/1920" in the second field