Can you add a feature to export DCPs to video files?
It's possible. However:
- This function would be almost completely unrelated to any other in DCP-o-matic.
- It is not quite as simple as ‘add a menu option to save as MP4’; there are many (potential) configuration options such as what format to use, what compression settings etc. to use for that format, what to do with sound (fold it down to stereo? compress it?), whether to burn in subtitles, etc. etc. etc.
- It seems to me to be a task which would fit much better in something like Handbrake or one of the FFmpeg front-ends.
- There is enough to do already!
This is not to say it won't happen, but just to explain why it is not a priority at the moment.
There are some notes here on how you can convert DCPs to other formats.