1. A system comprising: a camera configured to capture video data; a buffer configured to store the video data captured by the camera; a sensor data analysis module configured to determine an emotional or cognitive state of a user based at least in part on sensor data representing a physiological condition of the user; and a recording module configured to: detect a change from a first emotional or cognitive state of the user to a second emotional or cognitive state of the user; in response to detecting the change from the first emotional or cognitive state of the user to the second emotional or cognitive state of the user, create a video segment that includes at least a portion of the video data already stored in the buffer at a time the change from the first emotional or cognitive state of the user to the second emotional or cognitive state of the user is detected; capture additional video data after the change from the first emotional or cognitive state of the user to the second emotional or cognitive state of the user is detected; add the additional video data to the video segment; detect a change from the second emotional or cognitive state of the user to a third emotional or cognitive state of the user; cease adding the additional video data to the video segment based at least in part on the change from the second emotional or cognitive state of the user to the third emotional or cognitive state of the user; and store metadata with the video segment, wherein the metadata indicates the second emotional or cognitive state of the user.