The BBC wants to let viewers catch-up with television programmes via the net but the plans are proving controversial.
Favourite shows such as EastEnders will be available online
The world of on-demand threatens to shake traditional TV scheduling to its foundations as people increasingly pick where and when they watch video and audio content.
Media watchdog Ofcom estimates that so-called linear TV could be reduced by up to 30% over the next five years as a result of the wave of on-demand programming competing for viewers' time.
The BBC's on-demand plans, described by Mark Thompson as one of the most important projects undertaken by the corporation, will allow viewers to
watch popular TV programmes from the previous week's schedule on their computers or via cable TV.
To watch programmes on their PCs, viewers will have to download a piece of software known as the iPlayer.
Both the service and the iPlayer tool will be available once the BBC Trust - an independent body that replaced the Board of Governors at the beginning of this year - has published its final approval for the scheme in May.
The BBC Trust's initial approval comes with some interesting restrictions on the service as initially envisaged by the BBC.
As well as limiting the time that people can store programmes on their computers to 30 days, rather than the proposed 13 weeks, it has not approved the bookmark feature which would allow users to highlight a programme they wanted to watch ahead of transmission.
The Trust also recommends that the BBC adopts a more platform-agnostic approach to the digital rights management framework which protects the programmes offered for download.
The DRM framework currently relies on Microsoft technology but, the Trust says, the BBC must develop a more platform-agnostic approach "within a reasonable framework" which takes account of other technology, such as Apple and Linux.
For consumers, the BBC is determined to make the player as easy to use as possible. It will require users to have a broadband connection and the speed of their broadband service will dictate how long it takes to download programmes.
A 30-minute programme will take 15 minutes to download on a 1Mbps (megabit per second) connection and seven minutes on a 2Mbps connection. This will be VHS quality. To download programmes to DVD quality will take longer.
Offering audio and video content on-demand is an obvious next step for the BBC but it is entering a competitive arena.
TV on PC?
Broadcasters face stiff competition from players such as Apple
Some companies have described the BBC's iPlayer as anti-competitive.
As well as UK rivals such as Channel 4, which has recently launched its net TV offering, and ITV, which will follow suit this year, it faces competition from the US networks and Apple, which makes a host of TV content available via its iTunes service.
Apple is perhaps the biggest challenge to broadcasters, although the rich archive that the BBC has puts it "head and shoulders" above its rivals in terms of this particular challenge, thinks Arash Amel, a senior analyst with research firm Screen Digest.
But the more immediate challenge could be persuading consumers to change their viewing habits, he thinks.
"It is very early days. They are appealing at the moment to the early adopters when you consider that there are still houses in the UK that haven't even converted to digital yet," said Mr Amel.
Alongside the perennial issue of whether people want to view TV content on their PCs, the glut of applications that users will be required to download in order to watch content will also be a barrier to adoption, thinks Mr Amel.
"Consumers will have a computer littered with applications that take up space and memory. It would be like having to have separate set-top boxes to watch content from competing broadcasters," he said.
To simplify things for consumers, the answer would be to have a "Freeview equivalent for net TV", suggests Mr Amel.
The BBC's on-demand plans were recently assessed by broadcasting watchdog Ofcom as part of the Public Value Test that all new BBC services must undergo.
While Ofcom acknowledged that the BBC had to ride the wave of on-demand, it voiced concerns that the planned service could have a negative effect on commercial rivals and the DVD rental market.
It urged the BBC to consider excluding series stacking - which would allow users to view an entire series of programmes within seven days of the last episode being aired. It described this as the equivalent of "giving away the boxed set" of programmes.
In its conclusions, the Trust agreed with Ofcom, recommending a "tighter definition" of which series would be available in this manner.
Struggle for broadcasters
The watchdog estimated that the BBC's on-demand service could account for almost four billion viewer and listener hours by 2011.
Such services are likely to become more popular as devices, such as Microsoft's Xbox, increasingly bridge the gap between PC and TV.
According to a survey by Tiscali, which itself joined the on-demand market with its purchase of Video Networks International in August 2006, two-thirds of viewers are interested in watching on-demand programming on their TVs.
Almost half of those surveyed reporting that that they would watch less traditional TV as a result while 42% believed that traditional television scheduling will no longer exist in ten years.
A quarter said that traditional broadcasters would struggle against smaller niche programming providers.