How to make video tutorial for Free:
step1: In Ubunutu ,first install 'RecordMydesktop' software
step2: install 'Cheese' software , you can install it through ubuntu software center. This will show your face/video in the corner while recording Desktop
step3:Install 'Audacity' software , to remove noise in the recordings.
step4:Install Pitivi(video editor) , if you want to combine/merge the video file and audio file (noise removed) together.