switches to Adobe Flash has dropped Microsoft’s Silverlight technology for its online videos, switching to competitor Adobe Flash for the 2009 baseball season.

The move is considered a major blow to Microsoft, whose Silverlight, a programmable Web browser plug-in that enables features such as online animation, vector graphics and audio-video playback, was used by NBC in 2008 to stream Olympics content throughout the world.

Adobe and Microsoft have been battling it out in recent months for dominance in the Web video marketplace. CBS’ college sports group chose Microsoft’s technology last year after the computer company contributed free development and support to CBS.

The “Wall Street Journal” recently reported that Adobe’s Flash is installed on about 98 percent of Internet-connected personal computers, while Silverlight is installed on about 25 percent.

The MLB’s two-year deal will see Adobe powering the live streaming service as well as its highlight and library video clips. MLB and Adobe will also work on rich Internet applications, providing content and features outside of the Web browser. The MLB league gave no reason for abandoning Microsoft.

One area where Adobe has the upper hand is having the world’s major Web designers know and use their software. “It’s difficult to find designers who know Silverlight,” Scott Stanfield, chief executive of Vertigo Software, which specializes in building sites with Silverlight, told the “Journal.” “I can’t imagine a more hostile community [to Microsoft] than designers.”

Last May, Adobe launched the Open Screen Project, a group of 19 companies — including Nokia, QUALCOMM and Verizon’s wireless unit — to attract developers. The project promises developers that they can build software once, using Adobe’s technology, and have it run on PCs, mobile phones and televisions.