In your assets library, select the video file with which you want to work.
On the ribbon, click the Manage tab.
In the Actions group, click the Edit Properties button.
In the Edit Properties dialog box, click the Change Thumbnail link.
Upload three video files using each of the previous three methods to designate the thumbnail image.
From the three options that appears click the Use a picture from a web address option.
Type the web address for the image.
Click the Preview button.
Click the Save button.
In the Related section, click the Add New Item link.
In the Add A Document dialog box, click the Browse button.
In the Choose A File To Upload dialog box, select the file that you want to associate with the video.
Click the Open button.
Click the OK button.
Fill out the metadata information.
Click Save.
