Some DefaultVideoSink methods are called once per sequence, but this
doesn't make sense as the DefaultVideoSink is connected to the
VideoGraph output. This CL calls the DefaultVideoSink method only for
the primary sequence.
The other problematic DefaultVideoSink method calls will be moved in
follow-up CLs.
This is part of the effort to prepare PlaybackVideoGraphWrapper for
multi-sequence.
PiperOrigin-RevId: 742625589
595b75b7d3