VideoReader: Fastest way to get all the frames?

Hi there,

I'm using `get_batch` to get all the frames from a 1 min video and I wanted to ask you if there is a fastest method to achieve this? I read the code from `video_reader.py` and I don't think so, but I just wanted to confirm.

Here is my code:

```python
vr = VideoReader(video, ctx=gpu(0))
n_frames = len(vr) # 1800
frames_indexes = list(range(0, n_frames)) # [0, ..., 1799]
frames = vr.get_batch(frames_indexes).asnumpy()
```

Thank you.