What is the optimal length for an Internet video?

Answer:

No longer than three minutes, somewhere between 2.5 and 3 minutes.

If the video is longer than that, the number of people who stay till the end declines sharply.

So, if you want the maximum number of people to watch your video all the way through to the end, three minutes is the absolute limit.

But, if you're selling something, you don't necessarily care about getting the maximum number of viewers to watch all the way through to the end. What you want in this case is that the maximum number of viewers take a certain action, your MWR (MWR = Most Wanted Response).

By tailoring your sales video to three minutes or less, you may be maximizing the percentage of people who hang in to the end, but you may fail to convey all the info needed to trigger your MWR.

Creating multiple part videos might be an interesting option.

Part One for the people in a hurry and Part Two and beyond for the viewers who have the time and motivation to dig in deeper.

Interesting links:

Inmanstories, producers of Turnhere

Rocketboom

Ken McCarthy's System Video Blog