16. A computer-implemented method comprising: as implemented by one or more computer systems comprising computer hardware and memory, the one or more computer systems configured with specific executable instructions, receiving a designation of a reference video for conducting a search; assigning an object reference to a shape in a first video frame of the reference video and in a second video frame of the reference video; determining a first angle between the shape and a fixed axis in the first video frame; determining a second angle between the shape and the fixed axis in the second video frame; generating a reference textual representation of actions depicted in the reference video based at least partly on the object reference, the first angle, and the second angle; comparing the reference textual representation with a plurality of textual representations generated from videos stored in a library of videos; and generating video search results based at least partly on the comparison.
16. A computer-implemented method comprising: as implemented by one or more computer systems comprising computer hardware and memory, the one or more computer systems configured with specific executable instructions, receiving a designation of a reference video for conducting a search; assigning an object reference to a shape in a first video frame of the reference video and in a second video frame of the reference video; determining a first angle between the shape and a fixed axis in the first video frame; determining a second angle between the shape and the fixed axis in the second video frame; generating a reference textual representation of actions depicted in the reference video based at least partly on the object reference, the first angle, and the second angle; comparing the reference textual representation with a plurality of textual representations generated from videos stored in a library of videos; and generating video search results based at least partly on the comparison. 19. The computer-implemented method of claim 16 , wherein the content of the reference video comprises a second shape, and wherein the reference textual representation is based at least in part on a movement of the second shape in the reference video.