You need to be sure that the replacement power lead you buy is compatible with your video / DTT receiver model. To do this buy exactly the same DTT model as you already own. This new model will come with a compatible power lead for your older DTT and as a bonus you will end up with a backup DTT.
In your original question you wanted to keep it a secret about which model the power lead is for. Buying it again will continue the secret that you already owned that model.
NS, August 2012