Hello.  I am trying to use Movie Maker on Windows 10 and on my Windows phone.  The files won't open... on my laptop, they load forever with no error message.  On my phone, I get the error:  "Video could not be decoded" .  I get the same error from other video editors.  

I tried to switch the "open as" to Movie Maker (according to a YouTube that works) but Movie Maker isn't in the list of apps that come up in Win10 to choose as default.

What do I do to get these mp4s recognized and editable ?  

THANK YOU.

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