How to open a video file in Windows using the Ubuntu terminal?

So I am learning the Linux/Ubuntu command line. One of the things I want to be able to do is to use the Ubuntu terminal (Windows Subsystem for Linux) to open video files (mp4) on my computer (Windows 10).

I have tried VLC and MPlayer, but when I run vlc filename or mplayer filename, it gives me a very long error. It seems like it is running, but only shows text and then gives a long error.

You can do that out-of-the-box (official docs):

WSL can run Windows tools directly from the WSL command line using [tool-name].exe. For example, notepad.exe.

Applications run this way have the following properties:

• Retain the working directory as the WSL command prompt (for the most part -- exceptions are explained below).
• Have the same permission rights as the WSL process.
• Run as the active Windows user.
• Appear in the Windows Task Manager as if directly executed from the CMD prompt.

Windows executables run in WSL are handled similarly to native Linux executables -- piping, redirects, and even backgrounding work as expected.

If something fails, you could post a pastebin of the error/s, plus the output of

$ which vlc
$ which mplayer
$ pwd

Also, try other Win commands, as e.g. in the link above, to see if they work.