It was the new W10 update and had to fish for my VLC.exe to open these up.
Here's a tutorial: https://www.tenforums.com/tutorials/5507-choose-default-apps-windows-10-a.html which covers more than a few ways.
In Win 10 i want to choose my video player but the Default Application list doesn't allow me to search on my computer and select my favorite program. i hate this behaviour

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