Screencastify is a chrome extension that will help you to record screen activities as videos and posted into youtube. It will record all the screen activities inside the tab. You can also add your voice into the videos. Screencastify does not depend on any other software i.e. Java, Flash or other plugins. Videos are recorded as webm/vp8 files with ogg vorbis audio.
You can simply add Screencastify on your chrome browser after the installation button will appear for start recording and stop recording. It has experimental desktop capturing support. So it can record anything on your screen. After record screen activities it will give a list of records. You can directly upload videos into youtube from this list.
This will help you to create presentations and videos tutorials but you can’t download the recorded videos into your system.