I am afraid that the jig is up:
https://www.youtube.com/watch?v=vQzaLEuWdhk - 6:39
The chorus in Bridges in the sky really does look like it features lip synching. James looks like he's hiding away from the audience so he doesn't get caught. As much as I love Dream Theater, I don't know if lip synching by the main singer is something I can stand behind.
This reminds me of Geoff Tate lip synching over Empire ten years ago. It's slightly disappointing seeing James going that way as well. I would like to see this addressed in an interview or a Q&A with the fans, becaue I would at least try to understand why James would opt for this solution.
Had he decided to let the audience sing the entire chorus or change the vocal melody, that could be justified. This way, with all due respect from a fan who spent an enormous amount of money on the band and attended seven shows over the last 13 years, all in foreign countries, I don't think it's particularly respectful to the audience to pretend you're singing when you're not. After all, it's James LaBrie, one of the greatest singers of all time. The fans hold him to a higher standard.
Of course, I am ready to be put in my place if anyone cares to justify this and has an insight into the decision.