Can you guys give-me any feedback with my first Ruby Script? + Extra questions

[Gustavo H M Silva]

Hi evebody!

I'm learning Ruby for a week now, and since I'm very bad at math, I've trying to use Ruby as a bridge to connect my work (I work with Digital Video) and my new programming skills, I've been thinking about how to do that and I think I finally get it. I can automate video transcoding and other relate stuffs with Ruby!

Well, 3 hours later I've made my first open source script in Ruby for converting videos to some formats and I would REALLY LOVE if you guys could take a look and give-me any feedback. I don't know anything about lean code and stuff so don't be scared. 

Also. I would like to know... There's a field for people who only code in Ruby? I'm thinking about learn Ruby + Glade and work with local codes instead of jumping to the "famous" Ruby on Rails. Any considerations about that?

The link for my code is: https://github.com/gustavohmsilva/RubyFFmpeg/

Kind regards;

Gustavo H M Silva