I have an HTC One phone. I was filming a video and in the middle of it, it stopped recording because I ran out of space on my phone. It says that it does not support playback of this kind of video. I am assuming that all the content is there, but it did not write to file properly or something along those lines.
Just make sure you have another video on the device (can be very short or long, any video from the same phone)
Have you tried playing the video on the computer using VLC media player?
If the video works all the way through, then use a video encoder or converter and convert/encode it to a different format and try playing the video on you phone.
E.g. 001.mp4 -> Adobe Media encoder(You can try encoding it back to .mp4) -> Output file: 001.avi or 001.mp4 -> Put on phone and try playing the video again.
Hope this works out for you
Keep in mind that this can only convert the video you actually have, so if the video was cut off during the recording then you can get that part of the footage back