I take videos of our daughter on my cell phone which is an Android phone. Those files are created as mp4 files. My SIL takes videos of our nephew on her iPad or iPhone and those files are created as mp4's, as well.

I can't watch the videos she sends on my phone but I can watch videos I make or ones my husband sends me (also Android) on my phone. Does anyone know why this might be?

Again, they're all mp4 files....