I seem to be going round in circles and not really getting anywhere.

On WinBB it seems it's only possible to render videos as .avi files. However, I'd love to have videos in mp4 with the H.264 codec.

What codec/settings/steps are necessary to create mp4 video files?

Guessing, one has to render to avi first and then convert? Are there any best settings in the 'save as video' for this?