SEATTLE (AP) — Microsoft Corp. is hoping to tap the explosive popularity of online video sharing by joining startups and major Internet rivals with its own video service.

"Soapbox on MSN Video" will let Internet users watch and post videos, rate or comment on them and share favorites by e-mailing them or linking them to their personal Web pages or blogs.

Rob Bennett, general manager of MSN's entertainment and video services unit, acknowledged that Silicon Valley startup YouTube Inc. has an early lead, having already attracted tens of millions of users in the year and a half since it launched. Rivals Google Inc., Yahoo Inc. and Time Warner Inc.'s AOL also have similar offerings.

But Microsoft believes there is "still plenty of room to innovate, and go beyond what I would say most services provide ... just sort of the basics, a very kind of primitive experience that is not that engaging," Bennett said. "It's not that fun to use. It just gets the job done."

During a preview Monday, Bennett said Soapbox videos will be displayed in slightly larger windows than those competing services offer, and users will be able to expand videos to the full screen while they are playing, rather than having to jump back to the beginning and start over.

Soapbox will group videos in various categories, including most recent, most viewed, most commented on and top favorites. It will let users "tag" clips with keywords designed to make them easier for people to find.

A beta "test" version will initially be available on an invitation-only basis to some Microsoft employees and regular MSN testers, Bennett said. He said Soapbox will be expanded to a wider audience "very quickly," but he could not say how soon.