Complex sentence: Quoting a techPresident co-founder as saying that Internet video was changing the political landscape, Seelye wrote that most U.S. presidential campaigns were now fully engaged with video, with seven of the sixteen 2008 presidential candidates announced their campaigns on YouTube.
Split into simpler sentences: Quoting a techPresident co-founder as saying that Internet video was changing the political landscape, Seelye wrote that most U.S. presidential campaigns were now fully engaged with video. Seven of the sixteen 2008 presidential candidates announced their campaigns on YouTube.