I suppose it is a splash screen.
When the program opens It says
Media VLC Player Portable
PortableAppscom / go/ VLCPortable
It disappears after a few seconds, and normally this would not annoy me, but it does in this case because it is superimposed on the video I am playing.
Who knows how to disable this? I'm guessing it is in an .ini file, but I wasn't able to find anything that I could identify as related to this.