I have a video where I have something that has writting on it. the words appear backwards. I tried the mirror effect but I really want to mirror the entire video not create an effect that shows both the mirror and the original. The horizontal flip doesn work as the words still appear backwards..
You haven't said which version of the program you're using or what your project settings are.
But assuming you're editing a 1920x1080 HD video, add the Corner Pin effect to the clip. Then, in Applied Effects, set the corners to these settings:
Upper Left 1920.0 0.0
Upper Right 0.0 0.0
Lower Left 1920.0 1080.0
Lower Right 0.0 1080.0