1. A system for dynamically creating a video composition comprising: a portable device comprising a camera lens, a processor, a memory device, and a display device, wherein the portable device is configured to execute video composition software, the software instructing the portable device to: a) record a first temporal part of a real-world event as a first video clip in response to a first user record input, wherein the user record input delimits a beginning of the first video clip; b) display an image of the real-world event while the camera lens is perceiving the real-world event during the recording of the first temporal part of the real-world event; c) stop recording the first temporal part of the real-world event in response to a first user pause input, wherein the user pause input delimits an end of the first video clip; d) display an image of an unrecorded part of the real-world event while the camera lens is perceiving the real-world event; e) display a transition selection toolbar as an overlay on the displayed unrecorded part of the real-world event while simultaneously displaying a record button, both the transition selection toolbar and the record button being actively user-selectable, and receive as input one of a user transition selection input indicating a transition selected from the displayed transition selection toolbar or a second user record input indicating selection of the record button; f) in response to receiving the user transition selection input, combine the first video clip and the selected transition to create the video composition; and g) save the video composition on the memory device as a single file in response to a user save input.