What is the ideal length of video content on the web

How much time do you have? Willing to watch an hour and a half documentary on global warming or do you just have a minute to catch the hottest uploaded video? Today, tv on the internet comes in many flavors and in many lengths. So I wonder how much time people are willing to invest on a show on the web. And I wonder if the ability to easily move that content from pc to another device affects how long you are willing to watch. Video content in all lengths and forms are everywhere and continue to be added at an amazing rate; still, how do you find what you want when you want. The thing about linear tv is they told you what you were going to watch and when; you changed the channel if you didn't want to watch. Now your program, your channel, your time is up to you, you only have to know WHERE to find it. Good luck.