Update - This from support:
In regards with your concern, we are currently looking up into this option to be added in the near future, this means that it will be now the device owner’s discretion if they want to have a longer duration of recordings or a shorter one once the device starts recording. The main reason why we set it up this way for now is mainly because we want to make sure that the battery operated devices will not drain fast as well as you can save data charges if you’re accessing the videos in mobile data.
Watch this space, let’s hope ‘near future’ means… well near!