Here is my three line summary of the talk. Environmental phenomena are caused by humans; and they affect human welfare. So, inherently, there are value judgements in discussions, which are hidden, and what is worse, refused to be acknowledged. Further, different approaches (political ecology, economics, conservation biologist, …) lead to different solutions — because the end goal is different for each.
Prof. Lele also made a reference to a paper by Max-Neef called Foundations of transdisciplinarity, which is available here (pdf); I think I should read it some time.
A very though provoking lecture, all in all.