Is the impedance controlled board necessary for my camera board?
I've had a quick browse through the datasheet and it seems that the highest data frequency can be about 270MHz.

In all likelihood, no, you shouldn't need the extra service. If it was something like USB 3.0 (@5Gbps+), or PCIe (@2.5Gbps+), then it would definitely be worth considering, but 270MHz is borderline between considering things as distributed vs. lumped, especially if the traces are relatively short.

The board will require careful design, that is for sure. Designing the board with impedance matched traces by design (even without the verification step they offer) should still be done, even if it is an approximation. Also, ensuring you observe differential routing requirements correctly is a must (don't start routing the '+' trace down one side of the board and the '-' trace down the other!).

If this is a prototype run, it's almost certainly not worth it in your case - if the prototype does fail you can always revision, though trying to get it right first time is better. If it was a high volume production run, it would be worth the extra as the cost of high volume would basically trump any the extra cost.

From what I understand, the "controlled impedance" option is basically just a case of using a higher spec substrate and them doing tests to ensure it is the required impedance, vs. making the trace a certain width and hoping it is correct. This related question is worth reading regarding that.