There are several options for professional AV editing on Linux. Lightworks
has some industry clout because it has been used on several award winning
and many successful box office hits. However they have been sitting on a
beta release for over 2 years now so that's a bit lame.
With a combo of Blender, Cinelerra, <FLOSS DAW>, kdenlive, Openshot,
FFMPEG you can achieve almost everything that Lightworks is offering
without spending any money on software. Cinelerra and Blender are capable
of pulling off the vast majority of what Lightworks is offering. IMO the
Lightworks interface is not more intuitive than Blender or Cinelerra. They
all have a steep learning curve and require extensive background knowledge
to generate professional quality output.
For proprietary Linux NLE software you can use Smoke and Maya from
Autodesk or Fabric Engine ( basically a proprietary clone of Blender
funded by AMD ) and for proprietary 3d generators you can use Massive from
the people behind Peter Jacksons animation technology or a selection of 3d
game engines like Unigine, Unity, etc... For a proprietary version of
FFMPEG you can purchase a license from multicorewareinc if you are a large
studio, scientific organisation or government agency and you meet their
strict guidleines on gaining access to their proprietary codebase. Hint.
First you need lots of money and second you have to be on the official
technology sharing whitelist.
There are also several open source 3d game engines like cube2 that have
advanced features and potential if you don't want to spend money on
software as well as the one built directly into Blender.
All the big names in the movie industry have embraced Linux (except AVID).
It's taking a while longer for the music software industry to get it.
The truth is if they don't catch up soon they will miss their chance. I
give it 6 months before the companies stubbornly clinging on to the
windows/mac platforms get slammed now that Steam for Linux has been
released and all those people who were only keeping a Windows box to play
games on are released from that burden.