Free Video Flip and Rotate

It's ridiculously simple to use - you literally just import the video, click on the arrow pointing the way you want to orient your video and click start.
The only problem I have with it is it often makes videos glitchy. They will stop for a split second during playback, just long enough to really annoy you , and it will happen several times over. The sound can come and go as well.
Depending on the intended end use for your video, this program can be just what you want, or quality deficient enough to look elsewhere.

Watch out for skeezy spyware that installs by default with this application. You can deselect it via a custom install, but you have to deselect 3-4 crapware apps.