Microsoft has launched in public beta MSN Soapbox, an online video service that would compete with Google's YouTube.

Like YouTube, Soapbox lets people upload video in almost any digital format. Users can then tag and categorize videos, so others can more easily find them. One difference is that Soapbox users can watch and browse from the same screen. But the site apparently supports only Internet Explorer and doesn't work with Firefox.

Microsoft was not immediately available for comment Friday, but the LiveSide blog reported that Microsoft this week moved the site from testing by invitation only to public beta, where anyone could check out the site.

What's unclear is Microsoft's decision to brand the site under MSN instead of Live, which is what Microsoft uses for its many online services, such as e-mail, search, and blogging. Microsoft continues to use its MSN brand with its online entertainment offerings.

Soapbox is the latest example of Microsoft's catch-up strategy to Internet companies that have been faster and nimbler at taking advantage of the popularity of Web 2.0 services, such as social networking and video sharing. YouTube, which Google bought for $1.65 billion, is the most popular video site, and MySpace, which was bought by News Corp., dominates social networking. Microsoft also trails in online search and advertising, with Google the clear leader in both.