Many people ask for Camtasia Studio replacement in Linux. Actually there are many solutions in Linux such as RecordMyDesktop, Vokoscreen, Istanbul, Kazam, ffmpeg, even VLC. But among the available softwares, I choose SimpleScreenRecorder. It is because (according to my experience) I get the best compromise between quality and perfomance. I ever tried many of them but my system crashes many time because of the resource requirement. Here is my simple explanation on how to use SimpleScreenRecorder and Keymon to create video tutorial (screencast, screen record). I assumed you have installed both of them.

Simple Screencasting Studio in Ubuntu Linux