It's strange that the yellow dot is at the front cos the yellow dot represents your base frame. Propagation works on a plus/minus basis from the base frame. You can increase the span by dragging its in/out points as you would a layer or a paint stroke's in/out points.
When using the Rotobrush tool it is a good idea to first stabilize the shot so that you have less work to do. Then split the layer up into 2-second segments cos Rotobrush can be quite computationally intensive. Also, some strategy should be put into place. I notice lots of folks use the Rotobrush tool similar to using one of the Paint Brushes. This is a wrong strategy simply because Rotobrush can slow down quickly and secondly, this isn't how rotoscoping should be done.
The old-school adage of breaking up your subject into different parts still stands except that now the segmentation is based on colour rather than motion and the parts involved.
So, be prepared to Rotobrush your subject procedurally, both in terms of time and in terms of content, rather than forcing the issue by solving the effect at one go.
When segmenting your clip in terms of time, take note that the Rotobrush tool can its brushes can be copied and pasted to another layer. Hence, stabilizing the shot as a pre-process provides additional productivity gains.
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