May I ask for specifics as to what you would call "useless"? Note: If you think there's a useless video that violates our rules, please contact the mods (or just simply report it). However, many people are interested in PTR news (e.g., showcasing new items, builds, cosmetics, or other new content) and don't want to invest time themselves (or simply can't get access to it). Therefore, what might be "useless" for you, might be the "bee's knees" for others. It's not always that obvious. If you feel though that you've been fooled into watching/reading something you didn't want to, you may ask the thread creator (or a mod) to edit the thread's title and add a "PTR" tag to it.
I personally don't think a separate section would be a good idea. We have that on the official forums and there you can see that often the most fruitful discussions about PTR content are happening in General Direction. After all, the PTR is about future content - and even when the PTR isn't up, many threads in General Discussion are about Diablo's future.
But that's just my opinion - happy to hear what others have to say and to discuss this further.