Open Movie Editor is a free and open source video editing program, designed for basic movie making capabilities. It aims to be powerful enough for the amateur movie artist, yet easy to use.
Inkscape is a powerful Vector graphics program, that can be used to create extensive title graphics, using different fonts and graphical elements, that can be easily overlayed onto a video with Open Movie Editor.
Inkscape is Free and Open Source Software, and has a large Community of Developers as well as Artist Users, and it is not only available for the Linux Operating System, but for other major Software Platforms.
Node based compositing is a flexible and powerful way to create new video filters by combining and connecting existing basic operations into effects and image processing algorithms.
Combined with the versatility of Color Curves, which can be added as Nodes to the Open Movie Editor Node Graph, you can solve most needs, even for advanced color manipulation.
It also allows for creating advanced green and blue screen keyers, and enables the development of custom despill filters as well.