And here we are: Attached to this post you can downoad the PHP script currently used on Loadiine.ovh for MP4 payloads
You can open it using an advanced text editor (Notepad++ is recommended) thus you can see how it works by yourself. Of course classic notepad works too but heh, not funny ;w;
The only variable which needs to be modified in order to make it work is the first one ($payload). Point it out to your payload's full name within same folder where the script is located and run it through your Wii U browser.
This have been tested on my remote server, obviously, but also on my local network using Wamp64. As I can't clearly state if each server is acting the expected way with this script, please let me know about errors you might encounters in its use, thank you :3
On another note
@Kafluke, if you decide to include this method on your official package later on, I'll gladly put a link on Loadiine.ovh inviting interested self-hosting users to download it if they wanna do so ^^