Short and to the point, but the answer depends on the format and platform.
In a 2018 Digital Trends report, Emarketer forecasts that social network video ad revenues will reach $11.69 billion by 2020, roughly double the $5.68 billion spent in 2017. With that much money in play, brands are asking more questions about the efficacy of the money they are spending, and one of the most prevalent questions is 'how long will viewers watch?'
The answer depends on the platform and the intent of the video. Is it on your website, or being posted on YouTube? Is it a testimonial or a product demonstration? Is the intent to inform or advertise? Is it on LinkedIn or Instagram?
The one constant in a content-packed world is peoples' attention spans are getting shorter and shorter. Naturally, it follows that videos should be only as long as absolutely necessary to get your point across. Not surprisingly, 75% of all videos published last year were less than two minutes long.
You better have good video editors too, because to maximize your production budget and ad spends, brands need to customize the video length depending on the platform. For example, Instagram videos averaging 26 seconds received the most comments, while Facebook audiences engage the most with one-minute long videos, and YouTubers engage most with two-minute videos. And then those damn Millenials, 75% of whom are too lazy to turn their phones horizontally when watching video on mobile devices so you have to make sure the standard format translates vertically. (Take heart, Millenial haters out there because last year 86% of all business-related videos were watched on desktop browsers.)
Whatever the platform, the dictum 'brevity is best' applies.
The second best piece of online video advice is to put your most important points first. You know those annoying ads you have to watch before you watch the video you really wanted to watch? The average consumer gives them 2.7 seconds before they skip to the main content.
If you can get past those first three seconds, though, there's some good news. Facebook reports 65% of people who watch the first three seconds of a Facebook video will watch for at least 10 seconds.
Still, 10 seconds is still a far cry from expecting viewers to watch your video all the way through. While videos under 90 seconds see an average retention rate of 56% to the conclusion, videos over 30 minutes retain only 10% of their audience. It's generally accepted across the video marketing landscape that 33% of viewers move on after the first 30-seconds of a video.
It's said everything new is old, and if that's the case, welcome again to the world of silent movies. Understanding the genius of Charlie Chaplin makes your video much more likely to be successful as 85% of Facebook video is watched without sound as are 80% of LinkedIn videos. I guess that means we should expect the black derby hat to come back into vogue as well.
According to Cisco, online video traffic will make up 80% of global internet traffic this year so avoiding it is no longer an option. And pretty much like everything else in American society, consumers have decided they like scrolling through videos the same way they like driving up to the fast food window and getting their food 60-seconds later before moving on to the next part of their day.
So while your videos might have to be short, at least offer them something other than empty calories.
Update: If you want to bury yourself in statistics about video marketing and why it's a necessity, BitDownloader has an incredibly comprehensive database of facts and figures.