It will be located in the C:\program files\WindowsApps\ and like I said, it's a protected folder and it's best not to mess with the folder permissions. I don't know what the consequences of changing the folder permissions will be. I would not delete anything having to do with this folder. I also wouldn't attempt to open it (on my main system).
I'll open it on my
test system to give you more information.
After I gave myself permission to open the folder (something which recommend not doing), I see many subfolders. Inside of these are the apps, however, they are
not normal desktop applications.
You may find an EXE in some of the folders, but I was unable to run those due to additional permissions which I don't want to mess with.
Since we know that the following command will open the App, explorer.exe shell:appsFolder\Microsoft.ZuneVideo_8wekyb3d8bbwe!Microsoft.ZuneVideo, then we can assume it's located in one of the 3 Microsoft.ZuneVideo folders shown above.
Running it directly may not be possible, if that is what you are looking to do.