Dr. Ravi Agrahari : My Current Guide and Ex-Prof. at Rau’s IAS Study Circle, Scientist at IIT, Delhi. Importantly, he is a current intellectual Scientist on IASmind.com for Science and Technology, Disaster Management, Environment, Ecology and Biodiversity. See, Environment & Ecology For IAS Main’s & PT 2016-17, Disaster Management For IAS Main’s 2016-17 Model Solved Questions. He also deals with huge IAS institutions as well as Sites. Here is the links and video which is given by Agrahari to IASmind. 

Updates, For 2017-18. 

In, Flavido.. Free Video For Aspirants. Both, English as well as Hindi..