Required. A time (frame) of a video to which this annotation
pertains. Represented as the duration since the video's start.
Output only. The confidence that this annotation is positive
for the video at the time_offset, value in [0, 1], higher
means higher positivity confidence. For annotations created by
the user the score is 1. When user approves an annotation, the
original float score is kept (and not changed to 1).
