private getVideoInBulk: BulkObservables<string, ResultList<Video>>
private getChannelInBulk: BulkObservables<string, ResultList<VideoChannel>>
private getPlaylistInBulk: BulkObservables<string, ResultList<VideoPlaylist>>
private getVideoInBulk: BulkObservables<string, ResultList<Video>>
private getChannelInBulk: BulkObservables<string, ResultList<VideoChannel>>
private getPlaylistInBulk: BulkObservables<string, ResultList<VideoPlaylist>>