In some of my development and training guides, I like to use screen record and then post the videos online. It can show you rather than reading instructions,(as they say a picture says a 1000 words).
In doing so I use Ubuntu alot and find that a simple screen capture tool to use is XVidCap, this can usually be found in the repositories and can be installed.
Quick Tip:
On most of the installations, it has not worked, you press the record button and nothing happens. A solution to this is to add some different libraries, go to the Synaptic Package manger and install the libavcodec-unstripped-52 package, this should hopefully sort out the problem, also there have been reports of disabling the audio (not that I have found this feature yet)
When I was first starting to use GIMP as a image editor it was full or pwerful features and for free. I was messing around and what I really needed to do was remove the white backround from images and make it transparent so I could use it in multiple instances on a website with different background.
This is a very simple approach and I am sure there are others, but this is how it do it:
Open up the imgae using the GIMP editor
From the menu select Layer -> Transparency -> Add Alpha Channel, You will notice that nothing happens, this is ok, it adds transparency information to the layer
Some images I find that Add Alpha Channel is greyed out, so use Delte Alpha Channel then redo the above step
Now, go to Select -> By Colour, then click on the white background in your image, you will see that it has selected all the white background area
To remove this and make it transparent, all you need to do is Edit -> Clear, you should now see that where the white background once was is now the grey tiles which show you it is transparent
Now Save your image
Any issues, or further suggestions, please let me know