When creating a "Line Scan" slide in a Movie Project in Motion Studio, you can define if the two videos start at the same time or one after the other.
Start Together means that both videos will start playing when the first video of the Line Scan transition is displayed. This keeps things "continuous" in the image. The second video will pick up where the first video left off. The two recordings will be synchronized in their playback.
Start After means that after the first video of the Line Scan plays, the second video will start.
In the attached MP4, you can see the differences in the two clock images. The top image represents a "Start together" selection. The clock hand continues throughout the entire recording. The bottom image represents a "Start after" selection. After the line scan, you can see that the minute hand returns to its original location and then the motion starts over.