    def _get_vids(self, path, vfeat_dir, annotation_path):
        """refactored from
        https://github.com/DmZhukov/CrossTask/blob/master/data.py
        changes: add `vfeat_dir` to check if the video is available.
        add `annotation_path` to check if the video is available.
        """

        task_vids = {}
        with open(path, 'r') as f:
            for line in f:
                task, vid, url = line.strip().split(',')
                # double check the video is available.
                if not os.path.exists(
                        os.path.join(vfeat_dir, vid + ".npy")):
                    continue
                # double check the annotation is available.
                if not os.path.exists(os.path.join(
                        annotation_path,
                        task + "_" + vid + ".csv")):
                    continue
                if task not in task_vids:
                    task_vids[task] = []
                task_vids[task].append(vid)
        return task_vids
refactored from
https://github.com/DmZhukov/CrossTask/blob/master/data.py
changes: add `vfeat_dir` to check if the video is available.
add `annotation_path` to check if the video is available.
examples/MMPT/mmpt/processors/dsprocessor.py