MOB is an extension specific to files used by an online service available in Singapore called MediaCorp Online Broadband Television (MOBTV). This service offered video content distributed using MOB files. Such content was most often protected by DRM (Digital Rights Management) technology.

With the acquisition of MOBTV by xinmsn, the MOB format was abandoned in favor of Silverlight files. Currently, MOB is a rare format and is considered obsolete.