The point of failure could be in several areas but the most common breakdowns occur at the video player. Below are common reasons why video ads will not display on mobile.
Sending a media file type that the video player does not support – the most common unsupported file format sent is a .flv (Flash) file. Most mobile devices do not support flash so these files will not be displayed. Flash is common in the desktop environment and many advertisers send this file format for mobile requests as well not understanding that it will display on few mobile devices. If advertisers do plan to send a flash file format, they should also make sure they send widely supported formats like mp4.
Sending a broken creative – an advertiser may send a file format type that is supported, such as mp4, but if the creative is broken or the URI to the creative file is incorrect it will not display. In addition, if the file is too large and takes too long to download or the server the creative is hosted on is slow to respond it could also cause the video player to time out and not play.
Sending invalid VAST – if VAST XML is sent that is not valid or contains errors, then the VAST parser may throw an error and the video will not display. Some VAST parsers are more forgiving than others, and they may let some VAST errors slide, but others may be more stringent and will not display the video if it detects any VAST errors.
Tracking Pixels Not Working – in this instance the video would display but if the advertiser did not include tracking URIs or they were broken then the advertiser would never record that the video displayed and might believe some other error was preventing it from displaying.
There are many other reasons why the video player might not display a video including connection speed, incorrect VAST version, etc, but these are the main causes. Most video players do not provide useful if any error messages for tracking down the cause of the error, so it can be challenging for publishers and advertisers to determine why a video did not play. Recent versions of VAST provide specific error codes that can be sent which identify the error, but until more video players implement this error reporting, tracking down the cause of the failures will remain a challenge.