Yes, attention spans are shortening, and audiences are getting tougher.

But the same people who can't handle more than five minutes of a whiteboard explainer video are quite content to sit through two hours of the latest "Star Wars" saga.

This is no paradox. The answer is found in the content. A "tribute video" for a family member can keep an audiences of friends and relatives sitting on the floor mesmerized for an hour. The content is compelling for them.

A well produced and paced opening "rouser" video for a large corporate meeting played in a ballroom at 8am can elicit standing ovations. I've seen videos in that arena lasting as long as 20 minutes elicit tears and cheers.

It's all about matching content and style to the audience. The length of the video has more to do with creative strategy than perceived attention deficit disorder. Every serious business video has a clear goal set out by management. That requires a strategy based on what good writing and production can deliver.

Here's what to consider:

1. What is the premise?
2. What is your proof?
3. Who is the audience?
4. What do you want the audience to do?
5. What motivates them? What's in it for them?
6. What "style" video is best for this audience? Humor? Interviews? Clever narrative? Heart tugging emotion?
7. What pacing (music, editing) of the video will drive the audience to accept the premise and act?

Given all that, you can make judgement about length. This isn't YouTube (although the video may have an afterlife online). You aren't spending the big bucks for a whiteboard video or a talking head. So forget the assumptions and tailor your video to your message and audience and the length will take care of itself.