replaced checkpoint folder with huggingface path (#8)

* replaced checkpoint folder with huggingface path

* Update llavaction_video_demo.ipynb

- changed header to note demo data (not model)
- model from HuggingFace directly

* Update llavaction_video_demo.ipynb

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Co-authored-by: Mackenzie Mathis <mackenzie.mathis@epfl.ch>

Author: yeshaokai