Right now , the way i see it is that you have the sky box and the HTS ( home theater system) connected to the tv separatly with hdmi cables and then you ran an optical cable from the sky box to the HTS.
This could work but would not be how i would set this up.
With the equipment you have now , the correct way would be to connect the "MYSKY" box hdmi out directly into the HTS hdmi 1 input and then select that input .
In the mean time your tv will be set and left to the input where the HTS out is connect , for example HDMI 1 .
Now when you want to watch a dvd , the system will automatically switch to the player and when stopped , the skybox sound and picture will go through it on the way to the tv .
You can pull out the optical cable by the way , not useful here .
If that answers your question please do not forget to rate or you can use the reply button before or after rating if you have other questions or still need help setting this up , thank you .