It is feasible to post a video link on Instagram stories only for users having verified profiles or more than 10K followers. Users can easily swipe up on your story by tapping on “See More” and get access to the link you post.
For Instagram posts, you can add the link in your description. However, it is not clickable. Hence, people place the link in your bio and write in your caption “link in the bio.” You can change links in the bio as many times as you want.