I’m not sure what you’re saying. It sounds like you’re saying that you renamed ‘reza1-mp4.axx’ to ‘reza1.mp4’.
What did you expect would happen if that is what you did?
What will happen is that if you try to open it, it’ll try to do so using the video player registered for .mp4-files. That will fail badly, because it’s not an mp4 file. It’s an encrypted AxCrypt file, and the player will probably give you an error message saying it can’t play the video.