mp4 video will no longer play I have an mp4 video on my Dropbox. I was able to watch it earlier with the Dropbox app, but now it asks me whether I want to view it with the Photos app or Video Player... and neither appear to work. 

I have tried saving the video to my device but still no luck. I am able to watch the video through VLC player with no issues but I am trying to post the video to Instagram, and Instagram can't understand it either. 

I can also view the video on my iPad... and I've tried force stopping my Android apps and restarting my phone but still no luck
Try using VLC, it plays most videos other players cannot and has a good interface. However, if this still doesn't work, try using Video Converter, Compressor and select the file then change it to an MP4 (I know it's already MP4, but this may fix any issues).

VLC: https://play.google.com/store/apps/details?id=org.videolan.vlc&amp;hl=en 

Video Converter, Compressor: https://play.google.com/store/apps/details?id=com.xvideostudio.videocompress