A recent update of Microsoft Internet Explorer 6, reveals a
bug feature which forces your visitors to enable embedded Flash content by click.
The reason this was implemented is a lawsuit lost by Microsoft, which was about them implementing technology into IE, and Microsoft even put up a page telling its users about the feature. A workaround for the problem can be found at MSDN, and since this is merely a Flash-only problem, but also affects Quicktime, Apple put up a workaround as well.
Choose your poison.