Having a problem playing mp4 video files :( Help! Can I get some help?

[lovemuziccst]

Having a problem playing mp4 video files Help!

I downloaded videos (mp4) onto my phone recently. I was able to play the videos at first, but now I am having problems with them. After adding new videos to my phone, I was able to play the first half of the video but when it reached the second half, it said that the video file is unsupported. How can this be? I made sure that the video format is mp4 and i was even able to play the front portion of the video, why did i get cut off? Can anyone help?

Some people said that it might have something to do with the official Twitter app, so i deleted it and restarted my phone several times but to no avail. My videos are also stored in the phone memory and not external memory, so the problem is not due to external memory card. Please provide me with assistance, thank you!

 

[kevinmccready]

Problem is the "Google Now Launcher" which doesn't find the right app. I used a different launcher which launched the videos no problem. Actually I still have a problem, which is telling the new launcher my preferred video player. Off to play now with the app permissions.