It's not working in animation mp4.

Recently developing with telegram api, the animation mp4 file only get first image with the library. For now just assuming the animation mp4 file format is not supported. 

[animation mp4 file](https://user-images.githubusercontent.com/60820399/130285063-8fcf4e64-12e1-44f4-82af-5526ae21806f.mp4)

