Video-on-demand (VoD) marks a major shift in the way we consume TV - rather than having to watch programmes when the channels think we should, with VoD you can take control and watch what you want, when you want. The result is no more sitting through programmes just because they're on.
However, true video-on-demand means sending an entire copy of each programme to everyone that wants to watch it - with files taking up over 350MB for an hour of video, that's a lot of data being shifted around.
ISPs have had to deal with a minority of users overloading home connections with the use of P2P (peer-to-peer) applications, but with the launch of legal download services from Channel 4 and future services promised by the BBC and ITV the situation could get much worse.
For example, some free broadband deals limit you to downloading 2GB of data or less a month - that only allows for around six hours of video, and that's before any other usage is taken into account.
Even accounts that are supposedly unlimited are subject to so-called fair usage policies, which allow the ISP to either restrict a customer's service or charge them for excessive downloads.
Channel 4's PC on demand service - 4oD - launched on 6 December last year. Channel 4 won't give precise figures for the number of downloads, but it is "pleased with progress," according Victoria Powell from Channel 4.
"There's been a high take-up with lots of repeat viewing, with demand for both free and pay services."
The service uses P2P to deliver programmes, and Channel 4 estimates that it takes one and half times the length of the programme to download - so a one hour documentary would take 90 minutes to download.
With regard to consumers' increased bandwidth usage, Channel 4 said that was a matter for ISPs and customers.
"It's an issue for the ISPs," said Powell. "If someone is a high volume user they should use the most appropriate service. It's not a Channel 4 issue."
This view was also largely echoed by the BBC Trust which is in the process of evaluating the BBC's proposed iPlayer video download service.
"We do not believe that the extra infrastructure costs will lead to an overall detriment to consumers, since if consumers do not value the ability to receive greater audio or visual content over broadband they will not subscribe to any higher subscription charges," the BBC Trust report stated.
NTL is looking into ways of alleviating the load P2P applications place on its network.
"P2P solves problems for the broadcaster, but not for the ISP," due to the demand it places on the network, according to Kevin Baughan at NTL.
The problem of P2P can be solved using a system NTL has successfully trialled called accelerated downloads. The system works by placing a number of servers in major metropolitan areas - such as London, Cardiff, etc. These servers are referred to as 'on the edge of the network' - so a user in London would see the London server on the edge of their network.
These servers hold legitimate P2P downloads - such as licensed television episodes and films. The user begins the file download as normal, except rather than downloading pieces from other users, their client pulls the content from the server instead, which is faster. As less traffic is passing between users' computers the load on the network is reduced.
"Placing servers on the edge of the network can manage demand for traffic," according to Baughan. "It places the content near the consumer."
"For companies that want to offer commercial on demand services, servers located in major metro centres are the answer to efficiently distributing content."
To help balance the demands of customers, NTL is currently trialling traffic shaping - which restricts users' download speeds at between certain hours - in some locations.
"We are trying to enable people to do what they want with their internet connection balanced with a fair approach to what they pay," Baughan said.
"The product has to work well for everyone and has to be affordable - otherwise you price yourself out of the market or cause problems for other users."
The ISPA (Internet Services Providers' Association) believes it is up to customers to ensure they're using the right broadband package if they want to download video.
"It's going to come down to market differentiation. We do have ISPs that offer unlimited packages, but people have to pay for them," said Brian Ahearne of the ISPA.
"People use the internet for a variety of different uses, so it's up to them to find the most suitable package.
"There is a great deal of diversity in the market. ISPs should give accurate information to consumers to allow them to make an informed choice.
"The market will sort itself out - as demand for bandwidth increases, so the market will adapt to it."
A recent review by Ofcom on the BBC's proposed iPlayer service concluded that there would be an increase in customers' broadband usage:
"The average broadband customer, using the proposed internet-based services would involve downloading an additional 3GB of data per month. The costs of the broadband capacity required to support the services could in aggregate be between £399 million and £831 million over the next 5 years."
However, Ofcom also notes that connection speeds and download limits are likely to continue rising so the cost estimates set out above are likely to be at the higher end of the possible range.
"Some customers may have to move to more expensive broadband packages to use the BBC service," said Simon Bates from Ofcom.
"Consumers don't have to download video over the internet. The BBC and Channel 4 shouldn't be held accountable for additional demand. As long as there's choice there's no reason for the regulator to step in."
So if you want to take advantage of the new video download services, then you'll need to first check if you have a download limit on your account. If that's the case, then you could end up having to spend more on your broadband, at least in the short term.
Topic: Video on demand: can the web cope? (Read 467 times)