After inserting screen recordings in Storyline as Step-by-Step slides, you will be able to perform what is known in Storyline as "Action Fine Tuning." This useful feature allows you to change the starting and ending frames for each video clip in every slide.
You may already be aware that in Storyline, a single screen recording can be used in various ways (record once and use many). A single recording can be used as full motion Video on a Single Slide, or on many single slides as View, Try, and Test modes.
When inserting a recording on single slides, Storyline takes the entire full video recording and splits it up into smaller video chunks that altogether constitute the entire video. The length of each chunk on a slide depends on how long the person recording the screen spent between clicks.
A chunk of video on a slide can sometimes be longer than needed, resulting in large output files with less than ideal timing. The "Action Fine Tuning" feature in Storyline is where you can control the length of each video segment.
Action Fine Tuning is a bit of a hidden feature. The only way to get to it is by right-clicking a slide background or on the Screen Recording Action element in the Timeline.
After entering the Action Fine Tuning area, you can start adjusting/moving the starting and ending frames for the video clip segment by dragging the starting lines/markers along the timeline of the entire video.
You can precisely adjust the starting and ending frames by choosing the appropriate frame selection and clicking the Previous or Next Frame buttons.