I need to rename video files FROM my iPhone

I'm a photojournalist. Using my iPhone 6 Plus, I send video files to media outlets that subsequently download and edit them on computers. Because of this, it would be extremely useful to be able to re-title the video files in my camera roll before I send them. As most of you probably know, when you create a video on your iOS device, it creates a file name using a default numbering system, using something like 'IMG_12345.' This applies to videos that you take using the camera, and videos you export to your camera roll with iMovie (when you save an iMovie project to the Camera Roll, it doesn't give files the same name that the movie title is.)

Is there some way that I can rename video file names in the Camera Roll? I have used the app "Photo Manager Pro", but it's unreliable at best.

I've read that it's extremely simple on Android phones!