How can I access a new variable within a template?

[gnawph]

I've used this tutorial to make a simple page. The goal is to create a movie viewer. I need to have access to a new variable inside of a template file so I can use conditionals on my new variable to make something happen.

For example here is my ideal template:

<div>
     <if condition="$my_new_variable">Do this</if>
</div>