Office 365 -- PowerPoint -- Record in PowerPoint and Export Video.

Instructions

Recording in PowerPoint:

1. Open the slide you want to start recording from.
2. Near the upper right corner of the PowerPoint window, select Record.
3. Choose from two options.
4. When you're ready, select the round, red Record button, wait for the countdown, then start speaking.
5. To record from a specific slide, go to it and then select Record.
   
   
6. Allow "Microsoft PowerPoint" to access the camera.
   
   
7. This sign indicated that recording is during the process.
   
   
   
8. Pause - to pause a recording.
   End Show - to end a recording.
   
   

Export the video in PowerPoint:

1. When you're done recording, save and share your presentation as a PowerPoint file or video.
   Select File
   Choose an option like Save or Export.
   
   
2. Select the Files Format based on the presentation.
   
   
   
3. Typed file name
   Choose an option Export.
   
   
   

For more information: 

1. Here is the link to https://support.microsoft.com/en-us/office/record-a-presentation-2570dff5-f81c-40bc-b404-e04e95ffab33 for recording in PowerPoint.
2. Here is the link to https://support.microsoft.com/en-us/office/turn-your-presentation-into-a-video-c140551f-cb37-4818-b5d4-3e30815c3e83 export the video.