This is from the Official TV LIcence website:~
Do I need a TV Licence?
You must be covered by a valid TV Licence if you watch or record television programmes as they're being shown on TV. It makes no difference what equipment you use - whether it�s a laptop, PC, mobile phone, digital box, DVD recorder or a TV set - you still need a licence.
You do not need a TV Licence to view video clips on the internet, as long as what you are viewing is not being shown on TV at the same time as you are viewing it.
If you use a digital box with a hi-fi system, or another device that can only be used to produce sounds and can't display TV programmes, and you don't install or use any other TV receiving equipment, you don't need a TV Licence
Here is a link to the site:~
http://www.tvlicensing.co.uk/information/index .jsp