  The objective of this paper is motion segmentation -- discovering and
segmenting the moving objects in a video. This is a much studied area with
numerous careful,and sometimes complex, approaches and training schemes
including: self-supervised learning, learning from synthetic datasets,
object-centric representations, amodal representations, and many more. Our
interest in this paper is to determine if the Segment Anything model (SAM) can
contribute to this task. We investigate two models for combining SAM with
optical flow that harness the segmentation power of SAM with the ability of
flow to discover and group moving objects. In the first model, we adapt SAM to
take optical flow, rather than RGB, as an input. In the second, SAM takes RGB
as an input, and flow is used as a segmentation prompt. These surprisingly
simple methods, without any further modifications, outperform all previous
approaches by a considerable margin in both single and multi-object benchmarks.
We also extend these frame-level segmentations to sequence-level segmentations
that maintain object identity. Again, this simple model outperforms previous
methods on multiple video object segmentation benchmarks.
