There are a bunch of video editors for GNU/Linux but most of them are difficult to use or fragile. Here is one that is both easy and robust while being moderately powerful. It doesn’t have all the bells and whistles of Cinellera or LightWorks but if you’re just producing a short video for YouTube, who cares?
Check out OpenShot. It’s in the Debian repositories. Do try the latest package in “unstable”. It is an improvement over the current package in “testing” and far ahead of the version in the current release, Squeeze. There is a missing dependency. You need to manually install yelp if it is not already installed to get Help to work. So far OpenShot has worked flawlessly for me and the GUI has been all I needed to get started. One of the most beautiful features is that it is “web-aware” in that it knows the setting needed for videos to upload to YouTube and other sites so you don’t have to tweak arcane settings, just a main topic. I like that. It eliminates a lot of trial and error. Even I can do titles, fades and transitions with no help at all. Copy-and-paste works well. This is another great addition to Debian GNU/Linux.
Despite being used by hundreds of thousands, donations are lagging for such a great project. Try it and donate what you can to contribute.