In order to create a dynamic recording from your screen recording, you have to record your screen recording as you would a dynamic recording, by starting with "Hey there". Please see this article for steps on recording a dynamic video.
Once you've created your screen recording video, navigate to "Video settings" in the top right
Scroll to the bottom to the section called "Convert into dynamic screen recording"
Click the purple "Create dynamic screen recording" button
Select the top option to "Personalize greeting & video background" in order to be able to insert a personalized greeting for each screen recording you are sending out
Once the screen recording is converted, upload you prospect list and start generating
Note: when adding your prospects, leave the "Background URL" column blank as uploading a dynamic background URL will override the screen recording.