The BBC's iPlayer made its public debut in July 2007
The BBC has created a version of the iPlayer that works with both Mac and Linux computers.
The two systems, which have been able to stream BBC programmes via the iPlayer for a year, will now be able to handle downloads.
The BBC, working with Adobe, has developed the new version, known as BBC iPlayer Desktop.
The Corporation also ran tests of a system to help ISPs cope with increase in traffic generated by the iPlayer.
The iPlayer is the BBC's online media player that lets viewers stream programmes for up to seven days after broadcast or download and watch them for up to 30 days.
When the iPlayer first launched the BBC was criticised for producing versions that only worked with Microsoft's Windows XP and which used Microsoft's digital rights management (DRM) system to enforce viewing restrictions.
The BBC's head of digital media technology, Anthony Rose, who is responsible for delivering the next generation of BBC iPlayer, said the structures put in place by the BBC Trust on how the iPlayer can operate meant DRM was a necessity.
"The BBC Trust said we could make content available for seven or 30 days after broadcast," he said. "The ability to take things away after some time requires DRM."
The new version of the iPlayer has been written with Adobe's AIR technology which aims to make it possible to create applications that can be downloaded to your computer, rather than just embedded in browser web pages as is possible with the widely used Flash software.
Those who want to try the new player must first install Adobe AIR and then get the trial version by signing up to be an iPlayer Labs tester via the iPlayer site.
A beta version of the BBC iPlayer Desktop that uses the Adobe AIR technology was made available on 18 December with a finished version likely to be released in February 2009.
The cross-platform nature of Adobe AIR means the iPlayer will work with Open Source and Apple Mac computers "out of the box" on 18 December, said Mr Rose. It fulfilled the Trust's demand that the iPlayer be "platform neutral", he said.
Mr Rose said the iPlayer now supported three separate DRM technologies: Microsoft, Adobe, and the OMA standards for mobiles.
"We may embrace other DRMs as needed," said Mr Rose, adding that putting the iPlayer on phones, game consoles and many more computers was helping to drive the success of the application.
At the same time, said Mr Rose, the BBC has carried out tests to help ISPs mitigate the bandwidth demands of iPlayer users.
In early 2008 ISPs complained that the popularity of the iPlayer was putting a strain on their networks and forcing up their costs.
Net provider Plusnet published figures which suggested the cost of carrying streaming traffic increased from £17,233 to £51,700 per month largely because of the iPlayer.
The BBC has worked with British company Velocix to test a system which puts servers in ISPs that store, or cache, the most popular iPlayer programmes.
Mr Rose said smart software in the iPlayer would check these caches to see if the programme a user wants is loaded locally on a caching device near the user. Streaming from within an ISP's network cuts the cost of transporting that traffic for both the BBC and the net supplier.
It was up to ISPs now to get hold of the caching boxes and install them, said Mr Rose.
"The BBC is not building its own content delivery network," he said. "But we can help move the market in this area."
Mr Rose said it would establish commercial relationships with ISPs that use the caching technology in the same way it did with other firms that carry or broadcast BBC content.