TV shows like Doctor Who are expected to be available for download later this year after the BBC Trust gave initial approval to the BBC's on-demand plans.
The BBC's plans will allow viewers to download shows like Doctor Who
Under the proposals, viewers will be able to watch popular programmes online or download them to a home computer up to a week after they are broadcast.
But the trust imposed tough conditions on classical music, which could stop a repeat of the BBC's Beethoven podcasts.
Full approval of the on-demand plans will follow a two-month consultation.
After that, the BBC will be able to launch its long-awaited iPlayer, a computer application which allows audiences to watch or download any programme from the last seven days.
A programme will remain playable for 30 days after being downloaded or seven days after being watched.
The BBC Trust, an independent body that replaced the corporation's governors at the beginning of 2007, said the on-demand plans - which also cover cable TV - were "likely to deliver significant public value".
Programmes like Planet Earth could be available for longer
But it agreed with broadcasting watchdog Ofcom, which said earlier this month that the iPlayer could have a "negative effect" on commercial rivals.
As a result, the trust has imposed several conditions on the BBC.
It wants the corporation to scale back plans to let downloaded "catch-up" episodes remain on users' hard drives for 13 weeks, suggesting that 30 days is enough.
Chris Woolard, head of finance, economics and strategy at the Trust, defended the decision to cut the storage time.
ROLE OF THE BBC TRUST
Replaced BBC Governors
Twelve trustees appointed by the Queen on ministers' advice
Trustees earn about £35,000 a year
Independent of BBC management
Work on behalf of licence fee payers
Ensure value for money
Set limits for BBC services
Handle appeals from BBC complaints process
When people record a programme at home "if they don't look at it within 48 hours, they don't look at it at all", he said.
But some shows will be able to remain on a viewer's computer beyond the standard seven-day window using a feature called series stacking.
Every episode of a "stacked" series would be made available until a week after transmission of the final instalment.
Trustees said the BBC needed to be clearer about which programmes would be offered on this service - but suggested "landmark" series "with a beginning and end", like Planet Earth or Doctor Who, should be eligible.
The trust also asked the BBC to explore ways of introducing parental controls to its on-demand services, as it is worried at the "heightened risk of children being exposed to post-watershed material".
1.4m people downloaded Beethoven's symphonies from the BBC
Podcasts also came under scrutiny, with the Trust recommending that audio books and classical music be excluded from the BBC's download services.
"There is a potential negative market impact if the BBC allows listeners to build an extensive library of classical music that will serve as a close substitute for commercially available downloads or CDs," it said.
The news will be a disappointment to the one million people who downloaded Beethoven's symphonies in a Radio 3 trial in 2005.
But trustee Diane Coyle admitted the board "could still change its mind if there was a public outcry and it was backed up by evidence".
Licence-fee payers can now have their say on the BBC's plans, and the trust's conditions, in a two-month public consultation.
The trust said it expects to publish its final approval by 2 May.
The BBC Trust replaced the BBC's governors at the beginning of the year, and this is one of its first major decisions.
BBC media correspondent Torin Douglas said it was seen as the first test of the Trust's independence from the corporation's management, and that many would think it had passed it by imposing tougher conditions than Ofcom did in its own report on the issue.
Many of the BBC's commercial rivals had wanted Ofcom to take on the role of regulating the corporation.