Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Amazing concert, unwatchable Blu-Ray

Unfortunately, it is true. After waiting 20 years for this concert to be released, Universal has given us an unwatchable Blu-Ray. The concert itself is amazing. The video and audio are, on their own, fantastic. But they're out of sync. It varies, and certain camera shots are OK. But much of the time, you hear a cymbal crash notably earlier than you see Dave hit it. Or you hear Kurt slide from one note to the next a moment before he actually does it. If you're paying any attention at all, it quickly becomes unwatchable.The DVD is apparently fine, and while the quality won't quite measure up to the Blu-Ray, having it in sync is more important than the uncompressed audio and higher resolution we could have on BD. I haven't picked it up yet, but that's the only option. Don't buy the Blu-Ray. Universal denies there is a problem and says it's the fault of our equipment, but nearly every review of the Blu-Ray is negative. It's clearly a defective production.