After you've created your video sales letter content in a PowerPoint presentation, you need to save the PowerPoint file as a PDF and then open the PDF in full-screen mode. Now you need to use screen recording software such as Camtasia or Descript to record yourself going through the presentation. When you're finished, save the video as a .mp4 file and upload it to your sales funnel. Do NOT to use the built-in powerpoint presentation recording option to record your VSL because it's not very good. It will create pauses, gaps or delays as you transition between slides which will break the flow of your VSL.