The steps you provided are the ones I followed, and as I reported above, the video file was not successfully loaded back onto the iPhone. To be more specific, it went back on, but not in the Photos App's Camera Roll (where it was before I moved it off the iPhone and onto my PC). Instead, I could only view it using the Videos app, and since the video was taken in portrait mode it appeared turned by a quarter turn when viewed in the Videos app, which made the user experience of viewing it horrible. Plus, the ultimate object of this action was to share it with a family member via AirDrop, and that is not possible from the Video's app, only from the Photos App.
Plus, there was another huge problem. When I synced the movies, iTunes somehow interpreted that to mean I also wanted to sync my music (which I did not want to do because I manage music on my iPhone manually, song by song, which isn't possible with the restrictive sync function of iTunes), and it deleted all the music off my iPhone. In iTunes there are separate check boxes for choosing sync movies and sync music, but for some reason checking the sync movies box forces iTunes to sync the music too, with horrible consequences in this case.
I appreciate your taking the time to send a detailed reply. Unfortunately, I'm still looking for a solution for getting this video file back into the Photos app (Camera Roll) of my iPhone where it came from in the first place.