Weird video player on iPhone lockscreen

That is indicating that you were streaming some music from somewhere. It appears that it was only a 15 second clip, but the entire URL should scroll, so you could see it. It could have been from a website or something like that. You can double-tap the home button and bring up the task switcher and swipe upwards on the music player to force it closed.

It is coming from something. If you check the URL, it should give you a hint as to where it may have come from. Do you play any games, as it could be an intro sound, etc.

Strange. I follow the URL, and I get an HTML error screen. I would go to Settings>Safari>Clear History and Website Data. Then restart the phone. That should clear it out. Seems it could be a website script.

Glad that took care of it.