A man claiming to be one of the Wolves fans who urinated on The Hawthorns pitch after the game against West Brom has described the stunt as a joke which has caused more bother than they expected.
The man, who gave his name as Alan Shinton, aged 33, from Wolverhampton, said: "Basically we were walking past the ground.
"The gate was open and it was just too inviting.
"We'd both had a drink. There was no malice involved and no criminal damage.
"It was just a bit of banter and we didn't realise how much bother it would cause. It was just a bit of a joke.
"I would understand if they banned us but at the end of the day there's people committing crimes a lot worse than that."
The two-minute YouTube video, called "West Brom v Wolves 2011: P***ing On Your Pitch", shows two fans running onto the Hawthorns turf in broad daylight unbeknown to stewards and security.
The video was uploaded to a YouTube account belonging to 'MrShinna 123' on Monday morning. The description said: "They may have won 2-0 but we had the last laugh."
The cameraman can be heard saying: "Here we are, he’s off, he’s p***ing on the Albion centre circle, I don’t know what to do here.
"Can I just say for the record, if it goes to court, it’s all peaceful and we did not mean to cause any offence to anybody associated with West Bromwich Albion."
The offender then takes the camera himself and records his accomplice bearing his bottom before security guards catch up with them.
West Bromwich Albion won the Black Country derby 2-0 thanks to goals from Chris Brunt and Peter Odemwingie.
A West Bromwich Albion spokesman said the club was investigating.
>More: See the video here