Lightworks was originally supposed to be on Linux around 2011 but there were numerous delays and the project finally went into alpha last year but it was very restricted in terms of access. It's not too open but Linux development has continued.
Announced today on the Lightworks Forums is finally a public beta of Lightworks for Linux. "Today we are releasing the first Linux Public Beta version of Lightworks, this means any user wishing to test the Linux Beta version can do so by visiting the link below, filling out the short form and agreeing to the Terms and Conditions... This Beta version contains the new EditShare Licensing Service (ELS) which will allow users to sign in to the application using their Lightworks Username and Password (an internet connection MUST be present on the system) When signing in each new user will be automatically given a complimentary seven day Pro license to test the Pro version of Lightworks, this is renewable at the end of the seven days by simply signing back in to the application."