Within the first 48 hours of the upload: You can replace the auto-generated 9-second vid preview within the first 48 hours of the vid being uploaded by clicking the main drop down menu and selecting edit. Once on the profile page, click the gearicon at the bottom left of the vid and enter the start time in which you want the preview to begin. For example, if you want it to begin at the 1 minute 21 second mark, enter “1:21”.
After the 48 hours is up: You can upload your own customized 9-20 second preview by clicking the drop down menu > My MV Edit Profile. Once on the profile page, click on the gear icon at the bottom left of the vid. You will see “upload preview” underneath the vid image.