  This paper strives for motion expressions guided video segmentation, which
focuses on segmenting objects in video content based on a sentence describing
the motion of the objects. Existing referring video object datasets typically
focus on salient objects and use language expressions that contain excessive
static attributes that could potentially enable the target object to be
identified in a single frame. These datasets downplay the importance of motion
in video content for language-guided video object segmentation. To investigate
the feasibility of using motion expressions to ground and segment objects in
videos, we propose a large-scale dataset called MeViS, which contains numerous
motion expressions to indicate target objects in complex environments. We
benchmarked 5 existing referring video object segmentation (RVOS) methods and
conducted a comprehensive comparison on the MeViS dataset. The results show
that current RVOS methods cannot effectively address motion expression-guided
video segmentation. We further analyze the challenges and propose a baseline
approach for the proposed MeViS dataset. The goal of our benchmark is to
provide a platform that enables the development of effective language-guided
video segmentation algorithms that leverage motion expressions as a primary cue
for object segmentation in complex video scenes. The proposed MeViS dataset has
been released at https://henghuiding.github.io/MeViS.
