
Soapbox was launched in September and trumpeted as a possible 'YouTube killer'. The service has been available as a closed beta accessible by invitation only.
All users can view Soapbox videos, but only those with a Windows Live ID can comment on and upload new videos.
Soapbox is part of Microsoft's Windows Live online application strategy first outlined in 2005. The online services are designed to compete with web-based heavyweights like Google and Yahoo.
Windows Live includes a map service, messenger application and Microsoft's Hotmail client.
However, Microsoft will have plenty of catching up to do if it wants to compete in the video sharing market.
Research firm Compete estimates that Google Video and Google-owned YouTube give the search giant approximately 51 percent of the online video market.
Social networking site MySpace is the next-closest competitor with nearly 20 per cent of the market, followed by AOL with six percent.