Windows Media Player in Open with for .flv files

Im very happy with this contextmenu in 1703-version.
There is only one thing left ,which I could not fix still.
When I rightclick on a .flv-file , I can click on " open with " ,then another small menu opens with the apps available for playing the .flv-file.
I have MPC-payer and PowerDVD17 , and "look in the store" . What I miss in ,this list, is the WindowsMediaPlayer !
While the flv-files are standard opening with WMP , then why is the WMP not in the " open with"-list ??
In all my other file-types the WMP is present , not in flv...............
Can you help me with it , I searched a lot but can not find a solution for making it perfect.........

Yes, you are right indeed ! After making my choise with "Always use this app " , WMP plays the file immediately, but when clicking again you have to choose again ?!
When clicking on the flv-file; its standard playing with WMP and it is, coz when clicking the flv-file ,WMP plays it..........

Right, still I think it must be in the "open with"-list ,just like the other apps which can play flv-file !
Then why not WMP between them ?
In other file-type , for instance .avi , I can see all the apps (included WMP,with icon !) which can play avi , when clicking on " open with " ............

On my other Win10 1607-version , I see WMP between the other apps in the " open with " -list !
So, if I know where I can find the difference between 1607 and 1703 , for .flv , in regedit , we have the solution !!
But where is the regedit-file for this " open with " , where can we find these apps which are present in this list..........?