ffmpeg on android on a video http

I have to create such a file, on android from a video that is on http:

So I have the following questions:

1. Is there any way to use ffmpeg on android?
2. How much does it cost me to create this file? Consider that we do not use the wifi connection and use the data connection, how much would it cost me in megabite?

Assuming that the video is lasting 2 hours.