The upcoming Apple event will be the first time Windows users will be able to officially live stream an Apple presentation. You can see it on the fine print of the launch site. This time though the Windows 10 built-in Microsoft Edge browser has software that supports the same HTTP Live Streaming technology found in Apple software like Safari and QuickTime. Usually, only people using OS X, iOS, or an Apple TV device could do so. Some used workarounds through software like VLC.
Source: Apple Insider