Sitting near the Marseille fans I can assure you that they spent a great deal of their time shouting abuse and giving the nearest Albion fans the finger and various other unsavoury gesticulations. And I would never do that to my mother...
I was sat next to them in the ESL (never again - not because of the OM fans but due to the complete lack of effort by Brighton fans there) and they were fecking loud the whole match. However, it got very monotonous and I agree that explosive bursts from the crowd are much more exciting...