How can I set iTunes as my default .mp4 player?

I tried right-clicking on a .mp4 file and then clicked on "Properties" and then where it says "Open With", I clicked the button that says "Change..." but when the list of available apps to open the file appear, iTunes is not in the list, even after clicking on "More Apps"! I tried clicking on the "Look for more apps on this PC" link but I don't know the path to the iTunes executable so it runs and plays a .mp4 file whenever I double-click on it! Does anybody know the default install path to point it to this file? I looked for "iTunes" in the "C:\Program Files" and the "C:\Program Files (x86)" but came up empty.

Thank you,

EO