Instantiate a standard metdata object, populate the desired variables, and set the metadata object on the Media Heartbeat object. For example:
var standardVideoMetadata = {};
standardVideoMetadata[VideoMetadataKeys.SHOW] = "Sample show";
standardVideoMetadata[VideoMetadataKeys.SEASON] = "Sample season";
mediaObject[ADBMobile.media.MediaObjectKey.StandardVideoMetadata] = standardVideoMetadata;
var standardAudioMetadata = {};
standardAudioMetadata[AudioMetadataKeys.ARTIST] = "Sample artist";
standardAudioMetadata[AudioMetadataKeys.ALBUM] = "Sample album";
mediaObject[ADBMobile.media.MediaObjectKey.StandardAudioMetadata] = standardAudioMetadata;
See the comprehensive list of audio and video metadata here: Audio and video parameters.