Q: What platform would your recommend for an educator who wants to share his/her teaching practices online?

A: The best way is to create the educational video and distribute it at TED-Ed:

http://ed.ted.com/about

TED-Ed’s commitment to creating lessons worth sharing is an extension of TED’s mission of spreading great ideas. Within the growing TED-Ed video library, you will find carefully curated educational videos, many of which represent collaborations between talented educators and animators nominated through the TED-Ed platform. This platform also allows users to take any useful educational video, not just TED's, and easily create a customized lesson around the video. Users can distribute the lessons, publicly or privately, and track their impact on the world, a class, or an individual student. 

http://youtu.be/FfJ5XG5i2aw