Currently copies behavior of clip and image editors: - On file load, all strip will reference clip they're using - On adding new strip, clip would be referenced only if it've got zero user - On removing strip clip wouldn't be de-referenced to prevent clip editors pointing to zero-counted datablocks. Not actually ideal from human beings point of view, but referencing/dereferencing clip on each strip add/delete is getting crappy because of current logic of how clip datablocks are referenced from clip editor (which is designed to work fine with loading files without loading UI).