text/*
image/*
video/*app.OpenFile( "/sdcard/myVideo.mp4", "video/*", "Select a video player" );However, there is very little point in doing so in app.OpenFile unless you are going to create another app to open the file.
Usually, it is better to pick one of the commonest existing ones from somewhere like https://www.sitepoint.com/web-foundations/mime-types-complete-list/
Often, a wildcarded type will be better like
"text/*"
I'm 63 and every day I find something new I wish I knew.
I used to be able to learn quite a few of things I wanted to.
These days I forget more than I learn.
Believe me, the learning years are the most fun.