So far, it’s failing.
Gaming is a hugely popular category for video content on the internet. It's why Amazon acquired the video game streaming platform Twitch for $1 billion, and why Pewdiepie has the most popular channel on YouTube with 41 million subscribers. One of the most popular subgeneres of videos about video games is "Let's Play," which is pretty much exactly what it sounds like: people play through and often film their reactions to a video game.
YouTube personalities like Pewdiepie, Markiplier, and countless others are largely defined by Let's Play videos, which is why it seems rude that Sony is trying to register a "Let's Play" trademark.
The United States Patent and Trademark Office website shows that Sony initially applied for the trademark in October 28, 2015. In the application, Sony describes "Let's Play" as "Electronic transmission and streaming of video games via global and local computer networks; streaming of audio, visual, and audiovisual material via global and local computer networks."
Basically, if Sony managed to register this "Let's Play" trademark, the company would be in a good position to sue any YouTuber or Twitch streamer who used the term to promote their videos. Luckily, this hasn't happened yet.
On December 29, the USPTO responded to Sony's request, saying that it would likely refuse the application. I wish I could tell you it would likely refuse the application because that's a ridiculous term and broad concept to trademark, but no. The USPTO says that there's already a similar trademark from a company that provides a similar service.
The trademark in question is for "LP Let'z Play," which the USPTO describes as an entertainment service that provides "online and offline opportunities for video game enthusiasts to meet and participate in live video game tournaments and on-demand console gaming."
The similarities between Sony's application and "LP Let'z Play," according to the USPTO, are enough to refuse Sony's application because it "could give rise to the mistaken belief that [the goods and/or services] emanate from the same source."
If Sony wants to keep pursuing registering a trademark for "Let's Play," it now has six months to respond to the USPTO, and explicitly address these similarities.
Let's Play videos are huge, so it certainly makes sense for Sony, and any other big game company for that matter, to establish a brand associated with that type of media. Most game publishers already reach out to existing Let's Players to create sponsored videos, or just make their own. But for Sony to try and trademark a term and practice that rose organically out of the gaming community? That seems like an overstep.