Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
Your hitachi doesn't have an optical output. It does have a digital audio out connector, but it is a coaxial audio (spdif) connection, rather than optical.
While there are converters that would go from that digital coax to analog red/white stereo connectors, I wouldn't advise it in this case.
You'd be better off with a coax to optical converter, so that you can remain with an all digital signal. You'll get better sound this way.
Now if you have a cable/satellite box, dvd player, etc, you could connect the soundbar to it directly via optical.
The primary reason to use the tv audio out is if you have multiple sources, or if you're using the tvs internal tuner, apps, etc.
...by connecting to my sky box, when I watch a dvd or video will I be able to use the sound bar?
No, not without moving the cord around. That is what I meant when I said you're better off connecting to the tv if you have multiple devices.
If the only thing you used was the sky box, then it would make sense.
Otherwise, since you have dvd, vcr, etc connected to the tv also, you should buy the above converter to get audio from tv to soundbar for all of them.