Function which returns the ID of a video attachment

I’m building a theme which will accommodate a unique video for each page. I’ve created a test page with a test video attached to it, and am using wp_get_attachment_url along with the attachment ID to tell my video player where the source file can be found. What function and parameters will return the attachment ID number?

I’m not committed to this function, but am not sure what else to use. Perhaps get_children? If so, how would this work?

I’m a WP and PHP noob, so sorry if this is an easy question.