user: Question: Which On demand has a Pay and a Provider of Virgin Media (formerly NTL:Telewest)?
Columns: ['Provider', 'Years', 'Free or pay', 'Transmission', 'On demand']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['BT TV (formerly BT Vision)', '2006–', 'Pay', 'IPTV and digital terrestrial', 'Yes']
SQL:

assistant: SELECT "On demand" FROM "Table" WHERE "Free or pay" = 'Pay' AND "Provider" = 'Virgin Media (formerly NTL:Telewest)';