If you don't watch live broadcasts you don't need a TVL. Its down to them to prove you do watch them, unless you admit to watching live broadcasts. They do NOT have the technology to accurately prove you do, most of their vehicles don't even carry any kind of technology to do so and most TVL reps are in their own vehicles.
You very simply could say "I no longer require a TVL as I do not watch live broadcasts" and thats that. 'Enforcement Officer' - LEL, nothing but a scare mongering as with all of their letters that threaten court action, they require you to admit and sign an admission of guilt before they can 'get you'. I believe by 'live broadcasts' they are referring to ANYTHING currently being shown on the current schedule, regardless of it actually being 'live' or not. Important to note that they'll say almost anything to get their commission, TVL Enforcement Officers are door to door salesmen going to addresses where the system says there is not an active licence. They get around £20 per licence they secure.
It works on a very basic principle of no contact, no contract even if you've been paying it previously you can cancel it. Obtaining proof of channels watched through Sky, Virgin ect is in breach of the data protection act and these companies would be liable for it so they won't give that information up. It is purely down to TVL getting you to admit to it or them seeing you watch live TV which they must enter your property or see through a window visible from the street though I'm not sure on the legality of that, peeping tom?
If a so called 'Enforcement Officer' attends your property, they have ZERO right to enter without your permission. Keep your TV out of view/muted or turn it off if they attend, even so they cannot prove that what they can see or hear is a live broadcast its just better to be safe than sorry.
If they get a warrant to enter your premises unplug it completely requiring them to plug it in and if they do plug it in and switch it on, thats not YOU watching it and it is still not proof that YOU have been watching live broadcasts. You don't even have to talk to them or answer the door to them, you don't have to tell them your name.
Lack of a TV licence is NOT against the law. You are free to have TV to watch DVDs or play games, even catch up on demand is fine.
http://www.tvlicensing.co.uk/check-if-you-need-one/topics/technology--devices-and-online-top8
https://www.facebook.com/activeresistancetothetvlicence - I know, I know.. facebook but there is a good place to ask questions - I've looked into it myself and their statuses are accurately correct though they do bang on about the morality of the BBC a little too much and jump on the paedo bandwagon to convince people, I think an admin of the group has a vendetta against the BBC.
However, plot twist I pay for a TVL but we all need to make savings somewhere and if you don't 'need' a TVL then don't pay for one and save yourself some money.