Here's the legal bit
Sky Go and Sky Go Extra
UK/Ireland only. Streamed via broadband/3G (charges may apply). Available on 2 registered compatible devices (content may vary). Some live TV programmes unavailable.
iPhone (3GS or above), iPad, iPod touch (4th generation or above) require iOS 5.1 or later, and available on selected Android devices with OS2.2x to OS4.2.1 (excluding 3.x).
Sky TV Customers: Live TV and on demand content available in line with your Sky TV subscription at no extra cost. Sky Movies 1&2 or Sky Sports 1&2 packs required for on demand Sky Movies or Sky Sports. Sky TV packages £21.50-£55.50 per month. ESPN costs extra.
Non-Sky TV Customers: Subscriptions £15-£40 per month. ESPN £9-£12 p/m extra (or standalone at £16). Monthly subscriptions renew automatically until you unsubscribe.
Sky Go Extra: Sky TV customers only. £5 extra a month. 31 days’ notice to cancel. Register up to 4 Sky Go devices, concurrent viewing on two devices. Download selected Sky Go content via WiFi (Unavailable on Xbox 360). Content depends on your Sky TV package. Movies Pack required to download movies. Max 2 downloads per programme. Content deleted from device 48 hours after viewing starts or no later than 7 or 30 days after download depending on content.
Sky Go Extra Offer: Sky Go Extra available free for Sky TV customers for the first two months. After two months you will continue to receive Sky Go Extra at £5pm extra unless you call us to cancel at least 31 days before the end of the two month period. Offer ends 31.3.2013.