Protests were mounted at BBC television centre in London and at BBC offices in Manchester on Tuesday 14 August.
The Free Software Foundation said that the BBC had developed its iPlayer at a cost to TV licence fee payers of £130m, but that it had been developed exclusively for Microsoft's operating system and with Microsoft Digital Rights Management.
The Free Software Foundation said this goes against the BBC Trust's principles - open access and independence from corporate influence.
"BBC values have been corrupted because the iPlayer uses proprietary software and standards made under an exclusive deal with Microsoft," said Free Software Foundation executive director Peter Brown on his blog. "Licence fee payers must now own a Microsoft operating system to download BBC programming."
A spokesman for the BBC said that it was in its interests to make its content as widely available as possible. "We are prioritising the largest available audiences - the 22 million people who are broadband connected in Britain first, of which PC users using Windows XP represent more than 80% of the market. Concurrently we are looking at Macs (about 5%) and Vista (about 5%). After that, the next biggest audience is the three million cable homes."
The BBC said it has invested in a multi-platform approach for the end-to-end production chain for iPlayer. But in order to make launch plans practical and manageable, it is launching to different platforms in phases, which will include support for the Mac in a future release.
"Microsoft believes that Digital Rights Management gives content owners control over how their intellectual property is used and allows content to be available to a much wider audience," a spokesman for the software company said.