What I want is to chroma key a short segment from one video strip (a title overlay in the middle of a longer video), over another video strip background. I can't see any compositing options in the Effect Strip and Strip Modifier menus except for alpha/mask operations. So looks like I need to generate an alpha on my own, and apply it that way.
However, the only chroma key I am aware of in Blender is in the scene compositor. So the only solution I've been able to come up with is create one whole scene dedicated just to the title overlay clip, use the Matte output from the Chroma Key node to render the grayscale matte to disk, then reimport the render into a strip in my original scene and use that as my alpha.
This works, but it seems like more steps than there ought to be. I'm used to editors like Final Cut Pro that let you generate mattes via modifiers on a per-strip level. Is there no simpler way to achieve the same thing?
At the very least, can I do something to avoid having to manually render the matte frames?