The rejection by the trademark office is due to the similarity to the website called jwplayer.com. That company hosts videos, ads and streams for prospective customers.
Their web address ends in dot com but I assume they bought the rights to dot org as well. I looked up www.jwplayer.com and found an interesting point about the company's beginnings. The "About Us" section on their website says this at the top:
"We're the New York-based start up that PIONEERED video on the web."
The word pioneer is not in all capitals on their website but I thought it was funny and worth highlighting.
It looks like jwplayer.com started in 2005. I assume that's when they filed for the trademark name.