Complex sentence: The music video portrays a wedding of a friend of Grand Corps Malade who pitches in to "save" the wedding from a terrible singer by calling on the help of Reda Taliani and fellow musicians, winning the previously bored invitees over with his song.
Split into simpler sentences: The music video portrays a wedding of a friend of Grand Corps Malade. When Grand Corps Malade sees the disastrous musical act hired, he pitches in to "save" the wedding party by calling on the help of Reda Taliani and some fellow musicians, winning the previously bored invitees over with his song.