The length of a video for a story varies. For a straightforward narrative, 10-15 minutes could be enough. But if it's a detailed, multi-layered story, it might take 30 minutes or even an hour to do it justice. Also, it depends on the audience's attention span and the platform it's being shown on.
Well, there's no fixed rule. Sometimes a 5-minute video can tell a powerful story if it's concise and engaging. On the other hand, a feature-length film that lasts over 90 minutes can unfold an epic story with depth. It all comes down to the content and how it's presented.
It really depends on the story. A simple story might work well in a short 5-minute video, but a complex one could need 20 minutes or more.