You can add any custom thumbnail image to the video you upload to and/or embed on the platform.
After adding the video to the lesson, roll the cursor over the video and click the "Edit" button.
You will see the information about the video file. Upon clicking on the white field, you will be able to upload your thumbnail image.
You can always delete or change your uploaded thumbnail image.
Since the most common video aspect ratio is 16:9, we recommend the same aspect ratio for your thumbnail image.