Over at Strings 2013, Shamit Kachru gave a nice talk on Calabi-Yau compactifications and Mathieu Moonshine. The talk is based on the recent paper arXiv:1306.4981 [hep-th]
For those interested in the geometric Langlands and S-duality, Frenkel gave a series of lectures while visiting Columbia University last year. His lecture style is wonderfully clear and masterful, reminding me of talks by Gukov and Kapustin over at Caltech. Enjoy. (Spring 2012 Eilenberg Lectures)