Instagram have set a parameter on the duration of the video on Instagram. they have raised the duration if we compare to their old parameters.
If you post a video on Instagram then the limit is:
minimum - 3 seconds
maximum - 60 seconds
and if you post a video in Instagram story then the limit is :
minimum - 1 second
maximum - 15 seconds
You can not post a video more than the limitation. you can crop the video on Instagram and can make it within the limit.