The guy in this video appears to be holding the same yellow sign as the man who was in the picture with the bomber. The yellow sign had the blacks for trump website on it. That is where I started searching. Here is the website address. These people were positioned behind Trump at many rallies.
http://gods2.com/
and here is the youtube video again
https://www.youtube.com/watch?v=TlnXTSvF34g&feature=youtu.be