By Laura Harding, PA Deputy Entertainment Editor The Beckhams have been sharing lovely messages for their eldest son Brooklyn Beckham as he turns 25. Victoria Beckham posted an old video of little Brooklyn at a Spice Girls gig, sitting on his dad’s lap and singing to ‘Viva Forever’. The proud mum captioned the cute video: “Happy birthday Brooklyn. We all love you so much. Generous, funny, talented with the kindest most giving heart.” The fashion designer also said how proud she is of him being a great son, brother, and husband, and that he always thinks of others first. “We are so proud of the…