You can use up to a 32GB card in your ContourHD 1080p. When that camera was first introduced, 32GB cards were not widely available and that is why the printed manual in the box references 16GB cards. Since then the microSD card market has expanded and so your camera can use a 32GB card.
However, because the camera was not designed to use a card of that size, the memory card light will alway indicate that the card is full by showing a red light anytime you check the card status. This is true even when the card is not full. Other than that, it will function normally.