At the recent Southern Scriptwriters Festival myself and Danny did a talk on Writing for Online.
This caused a slight worry for us - as there isn't really much to say about the actual writing of online material. All the classic elements of writing remain the same. Just focus a bit more on high concept ideas and keeping it short. If you were already a comedy sketch writer for TV and were going to move across into online then the differences would be minimal. The only major difference I could think of was that the character and concept is much more important than any single film.
But what does change, when you are a writer, is something else. It isn't the script. Instead it is your role as a writer. Because the ideas are more high concept generally, it means that technical prowess and acting skills can be reduced. Now you can get more involved with the shooting and the realisation of your stories rather than handing the script over to a large crew. It is totally proactive.
To demonstrate how that can be true we knocked out a quick viral short in the lecture itself. It is, "If Cracker taught scriptwriting". The opening scene to Cracker is often used in writing lectures, so Danny felt it was ripe for a bit of satire. You can see the original scene here.
It is not a great viral. It took 10 minutes. I borrowed a jacket of Dan Pringle. It was shot on DV. Edited in 30 minutes. But it is out there and not on a page. That's the main thing.