In this movie, we zoom in towards the Sun, fading from a visible light view to data from the 304 Ångstrom filters aboard SDO and both STEREO spacecraft. We swing the camera around to a view of the side of the Sun NOT visible from the Earth. With the STEREO and SDO data mapped to the sphere representing the Sun, we see the dark sliver of "No Data" which slowly shrinks as the STEREO spacecraft move into position 180 degrees apart on opposite sides of the Sun (and 90 degrees from Earth).
STEREO data near the edge of the solar disk get stretched when projected onto a sphere and is responsible for the streaking on either side of the dark sliver. These data are sampled roughly six hours apart for each frame of the movie. Slight differenences in the six hour time step creates a slight 'jitter' of the dark sliver.