diff --git a/plugins/jspsych-video.js b/plugins/jspsych-video.js
index db5107f1..39ace459 100644
--- a/plugins/jspsych-video.js
+++ b/plugins/jspsych-video.js
@@ -99,8 +99,8 @@ jsPsych.plugins.video = (function() {
 
     var video_preload_blob = jsPsych.pluginAPI.getVideoBuffer(trial.sources[0]);
     if(!video_preload_blob) {
-      for(var i=0; i<sources.length; i++){
-        var file_name = sources[i];
+      for(var i=0; i<trial.sources.length; i++){
+        var file_name = trial.sources[i];
         if(file_name.indexOf('?') > -1){
           file_name = file_name.substring(0, file_name.indexOf('?'));
         }