Moodle 2.6 has a function of the $ OUTPUT object called pix_url that gets the image name, but it would not work for the video, another option would be to use some moodle variables and functions to get the path to the theme folder where your video is probably something like
<?php echo $CFG->wwwroot.'/theme/'.current_theme() ?>
By doing this you will have a URL that directs you to the folder of your theme, that is to add / caminodovideo /
Looking at the internal moodle code, it holds itself in this variable for many of its libraries such as /lib/outputrenderers.php and /lib/pagelib.php, so it is safe to use.