The supermodel - who embarked on a relationship with the singer when she was pregnant with daughter Leni, now six - feels "lucky" with their union and admits she never expected to achieve such happiness with anyone.
She said: "I feel so lucky to have found my husband especially at the time when I did. He is both what I always wanted and never thought I would have."
The couple - who also have children Henry, five, Johan, three, and Lou 11 months - star naked in bed together in the video for Seal`s new single -Secret- and the pair admit they didn-t need to stretch their acting skills too far during filming.
The 37-year-old beauty told Us Weekly magazine: "It`s the story of two people in love."
Seal, 47, added: "The song, the movie, it`s the story of our love."
Seal - who has legally adopted Leni - recently said he believes his relationship with Heidi works because they are "best friends".
He said: "I`m married and in love with my best friend. We go through everything together. We go through the same s**t that other couples go through; we disagree and have very few low points but we have a lot of high points because we just realise how lucky we are to have found each other."