NeoK12 is an educational website that provides videos and games on a variety of school subjects for use as instructional tools. Most of their information focuses on science (including chemistry, physics, and Biology) with additional videos on English, math, history, and music.
Youtube has many great chemical reaction videos, just search for chemical reactions. HowStuffWorks, About, and neoK12 have even more chemical reaction videos. Additionally, many chemistry documentaries feature chemical reactions. These videos can typically be found at a local library or online.