https://i.ytimg.com/vi/YjOSkSQtGOM/hqdefault.jpg All you wanted to know about Extruding in 2.5 Blender. Extrude Region Extrude Individual Extrude tip for angle extrusions. Praying Mantis tutorial mentioned in video is here: http://www.blendercookie.com/2009/08/28/modeling-a-praying-mantis/ Removing doubles Vertex Edge Face data in interface. source