By Jane Wakefield
Technology reporter, BBC News
If you are a fan of TV drama Lost but are not able to watch it on US TV, it is not hard to find episodes on the internet.
People are increasingly unwilling to wait for their favourite shows
Popular shows like Lost, Desperate Housewives and 24 are increasingly easy to find for free on peer-to-peer networks, often within minutes of airing in the US.
And many people outside the US are simply not prepared to wait until they come to their own small screens.
"Most episodes come online about half an hour after it first airs in the US," says Dr David Price, head of piracy intelligence at web monitoring firm Envisional.
"Someone with a fast connection in the UK can watch it before it airs on the west coast of the US."
The pirating of popular TV shows is a growing problem for the TV industry as viewers increasingly demand their own viewing timetables.
An on-demand culture plus the growing speed and uptake of broadband are making TV the most pirated asset on the internet, Dr Price says.
He estimates that must-see shows like Lost are getting over a million illegal downloads per episode - up from around 150,000 a few years ago.
"It is now as easy to download a TV show through a website as it is to set your VCR," Dr Price says.
"These days, missing a TV shows presents little problem to anyone with even a basic knowledge of the internet.
"Two clicks and your favourite programme is downloading, and with the advent of RSS technology, downloads can even be automated.
Some people want to watch TV on a variety of devices
"In effect, the internet is now a global video recorder."
Pirate Bay, a popular BitTorrent tracker website, has tens of thousands of people exchanging files, typically movies and TV programmes, at any one time.
At the time of writing, the latest episode of CSI New York has more than 1,000 people exchanging the programme from just one source and less than 24 hours after broadcast in the US.
And content downloaded from the net is usually ad-free - another reason for viewers to turn to the black market and for TV executives to get worried.
A 45-minute programme is typically around 350Mb in size and can take anything from two to six hours to download, depending on its popularity.
Once downloaded, programmes can be converted to DVD format and burnt onto a disc or converted for viewing on a PlayStation Portable, iPod video or another portable device with video playback, even mobile phones.
According to net analysts CacheLogic, up to 70% of internet traffic comes from peer-to-peer networks. The vast majority of this is video content, both movies and TV.
Peer-to-peer distribution system BitTorrent is responsible for around a third of this traffic, it estimates.
And it is estimated that the UK accounts for between 10-25% of all TV piracy, largely because most sought-after pirated content is US shows that have a natural audience in the UK.
One of the biggest problems in combating TV piracy is persuading people they are doing anything wrong.
"There has to be an education campaign," says Eddy Leviten, spokesman for the Federation Against Copyright Theft (Fact).
"We have to make people aware that it is illegal. It is infringing copyright. This is intellectual property that somebody somewhere has to pay for."
TV companies are increasingly making shows legally available online, with ABC selling episodes of Lost and Desperate Housewives via Apple's iTunes.
In the UK, Sky is also determined to capture the zeitgeist and make more programmes available legitimately.
"The evidence shows that there is a clear appetite for people to enjoy TV shows in a more flexible way and, as an industry, we need to give customers that flexibility," says Sky spokesman Robert Fraser.
"BitTorrent is responding to the demand of consumers and the industry has the ability to respond too," he added.
Sky has just started showing the third series of Lost, with episodes available for download shortly after their TV broadcast.
Dr Price says legitimate download services will help - but there must a bigger change in the TV industry. The waiting time for US shows will eventually disappear, he believes.
"The headline shows such as Lost and 24 will start airing in the UK at the same time as in the US," he predicts.