Any alternative of 'Camtasia Studio (Screen recording & video editing)' for Ubuntu?

I think you can use Kazam Screencaster for recording purpose and for editing those videos you can use Openshot video editor.

The combination of both will you provide functionality of Camtasia Studio.

Camtsio Studio = Kazam Screenscaster + Openshot Video Editor

Just open your Ubuntu Center Software (you can open it from terminal with this command: software-center) and search for screen record (for example) and you will find applications like Kazam, RecordMyDesktop or Istanbul which may do very well what you intend.

Here is a video review about Kazam: OMG Video Review: Kazam Screen Recorder Tool.

You have several options including gtk-recordMyDesktop (gnome) qt-recordMyDesktop (kde)

There is a full tutorial here : https://wiki.ubuntu.com/ScreencastTeam/RecordingScreencasts