Thanks Mike for the review. Above test in Travis is failiing at video/test/marionette/video_info_test.js:24:39, where its not able to find element app.thumbnail defined in video.js with selector css   'ul.thumbnail-group-container li'. 
This happens when there is no video loaded in video app. I am not able to replicate it on local machine. I am able to copy image file in temp folder ~/Library/Caches/TemporaryItems/device-storage-testing/videos/ and video app successfully loads video from the temp directory. 
The code to copy test video file is in test_common module as copyTestVideo Line 96.
It could be race condition where the video app is loaded before the file is copied in temp directory or could be a file copy failure.  Any idea, how to debug this?
You are right, I will move the call in video#launch definition.