The blurry result of the recording is usually caused by the automatic compression in Storyline when the Storyline project has a lower resolution than the captured area.
So, if you have created a Storyline project in one of the standard resolutions (3:4 = 720 x 540px or 16:9 = 720 x 405px), and your recording, for example, has a Full HD resolution (1920 x 1080px), the recording will be automatically downscaled and appear blurry.
In this case, we recommend adjusting the resolution of the project under the "Design" tab, in the "Story Size" section, or not setting the capture area larger than the project's resolution.
Additionally, in the publishing settings, you always have the option to adjust the compression of the videos under "Quality" (see screenshot).
