Intro

Linux Day and Ubuntu Intrepid Ibex are coming, many potential new users will try Linux for the first time and a part of them will remain with Windows or (worse) will switch to Mac OS X.
If you think "Linux ecosystem" is ready for the masses, You have just to show it!

Ubuntu Killer Apps (HD) from grigio.org on Vimeo.
(Go to Vimeo Site to watch it in HD)
Another good video service is Blip.tv, here is the same video.

Screencast what you like

Screencasting on Linux it's easy, install gtk-recordmydesktop and run it.
Now record what software you like and explain how you use it on every day or choose a topic to help new Linux users in simple tasks.
You can also record video and audio simultaneously with Compiz enabled.

Upload your screencast in High Definition (HD)

There are a lot of screencast about Linux, Ubuntu, Compiz,.. on YouTube, but this videos are far to be useful for new users, the quality is very low and the writings aren't readeable.

To have a screencast in HD you have to follow the Online Video Service specification and maybe to do some tests.

Vimeo: It supports HD only in 16:9, so choose a compatible screen resolution before recording.screencasting (ex. 1280x720) or adapt your 4:3 screencast to that resolution with Avidemux(*) adding black lateral borders.
YouTube: It supports HD but you have to convert(*) the .ogg video in .mp4 before uploading.

Some Samples

YouTube
YouTube HD (click on "watch in high quality ")
Vimeo
Vimeo HD

(EXTRA) Video Editing and Postproduction

If you want to add transition effects, titles or the soundtrack to your video the most usable & stable Video Editor for Linux is Kdenlive. If you think to edit your audio/video choose 25 fps before recording.

(EXTRA) Notify keyboard shortcuts and mouse position

It's possible to print on screen the shortcuts pressed with shortcut-notifier or if you need to hightlight the pointer position enable it in mouse preferencies.

Other Interesting Video Resources

Ubuntu Screencasts
Ubuntu Developers Channel
(Compiz) FusionCast
Inkscape Tutorials
Grafica professionale con GIMP (Italian)
Guia Ubuntu (Spanish)

 
(*) Avidemux supports many codecs but not .ogg directly. You can transcode the file.ogg in mp4 with:
mencoder INPUT.ogg -aspect 16:9 -of lavf -lavfopts format=psp -oac lavc -ovc lavc -lavcopts aglobal=1:vglobal=1:coder=0:vcodec=libx264:acodec=libfaac:vbitrate=4500:abitrate=128 -vf scale=1280:720 -ofps 30000/1001 -o OUTPUT.mp4
or
mencoder INPUT.ogg -aspect 4:3 -of lavf -lavfopts format=psp -oac lavc -ovc lavc -lavcopts aglobal=1:vglobal=1:coder=0:vcodec=libx264:acodec=libfaac:vbitrate=4500:abitrate=128 -vf scale=960:720 -ofps 24000/1001 -o OUTPUT.mp4
Thanks to Eugenia