For most content marketing videos keeping things short and sweet will get you more attention. The first 10 seconds of your video production has to grab your audience. Sometimes even a 6 second GIF will get the job done. Of course, the length of your video is platform dependent. The more captive audience you have, the longer the media can be, but even a corporate training video should be kept concise and visually stunning.
Video production and editing are all about the audience, keeping then engaged is the number one rule!