Why does my rendered video not animate? I have used Blender to generate a video clip using H264 and the clip works perfectly, however I need to add audio and some titles, so I have re-imported the clip into the video editor and added the other elements there. 

The problem I have is that when I export the video, it is not animated. What is exported appears to be a single static frame rather than the animation that is visible when one opens the clip in a regular video player. Unfortunately the clip is not highly mobile, it changes quite gradually, so it isn't very obvious in the preview, but it doesn't look to me as though the preview is animating it either. 

I'm wondering if there is something wrong with the time selection, but I can't figure out what is wrong with this: 


I am completely new to the Blender-as-video-editor world so I might be missing an essential step, but like most matters for the Blender noob, I have no idea what that would be because the interface has ten thousand settings and every tutorial or document is discussing a slightly different version.

What do I need to do to ensure my video is rendered with animation rather than static?
After struggling with this for a while I switched to a different video editing tool ( I used KDEnlive ) and used that to put together the complete video. It worked perfectly with Blender's exported video and was quick and easy to work with. A Swiss army knife is very practical when you don't have a screwdriver, but if you do have one, use that instead.