You can use the thumbnail access URL syntax to access the thumbnail associated with a video. The URL syntax allows you to define the size constraints of the thumbnail and acts as a convenient method developers to load thumbnails of a given MediaItem ID into an app or site.
The syntax is as follows:
http://cds1.yospace.com/access/d/u/0/1/thumb/{size}/{mid}?f={fid}
Where:
size - value is of the format WxH and is the bounding box of the required thumbnail. yospaceCDS will return a thumbnail that does not exceed the dimensions specified. Aspect ratio is preserved. Examples are 80x80, 128x75, etc. {mid} is the content ID of the video.{fid} is the ID of the Output Feed to which the access should be attributed. It is optional, however it will ensure that your thumbnail is delivered through the CDN that is associated with your account.