Rendered Video pages and added comment function.

-For Video model, completed index.html and show.html:
1. index.html shows all the videos and clicking on video title leads you to the video in show.html
2. show.html shows the video and comments
-Added comment functionality:
1. comment form with subject text and body textfield.
2. routes to create, where we manipulate params, create the row, and redirect back
3. once redirected, show.html shows the comment (most recent on top)
-More on the manipulating params. I sent params through params_helper to return :subject, :body, and :video_id