#3: They haven't said anything because things are in flux with the people involved in actually putting together the DVD and getting it out, and rather than release news that ends up being wrong next week when something else ends up happening that causes another delay, they are waiting until they know something concrete to give us.
It can be frustrating not only on our end, but also for the band, to have information put out there, and then have to keep retracting and changing it as other obstacles arise. I think it's a safe bet that unforseen things have popped up and that the band aren't getting answers with enough certainty that give them a comfort level that they can give us anything certain right now. Yeah, they could take a moment to let us know there is uncertainty, but I could also understand that they don't want to do that and appear like they don't have any control over the situation (even though they likely don't). I would guess it's something along those lines.
This all might be true, but a message like, "Sorry for the delay on the DVD/Blu-Ray, DT fans, but it's coming very soon, and trust us, it will be worth the wait! Just be a little more patient!" would take about a minute to type and post on FB or twitter. And fans would appreciate the band at least addressing the issue, instead of saying nothing.
Yeah, but just think about it. The first time we got the date was from the Eagle Rock trailer, and only when it leaked prematurely, when they re-released it there was no "May" in the video description. Then we had OTE prematurely estimating stuff, and the Mattivision (sorry if I misspelled) trailer was the only one that definitely mentioned May. Then we had all these distros and the range of dates from May through July and June to November. None of these announcements came from Dream Theater themselves.
The number and type of fans which get all their DT news through what they post on social media and who don't pay much attention to those either would go "what DVD?" or "what delay?" at that announcement. For all the rest of us, there's inties with two members of DT (JP, MM) which basically said that the DVD hasn't vanished into thin air, and that they don't know anything about a release date now but it's full of awesome stuff, different to anything they've done before, that the difference is the reason (or one of the reasons) why it's taking so long and that we just need to be patient. And JR through his Twitter and during his StageIt performance confirming basically the same thing. So that's 3/5 of DT telling us what they can about the DVD.
Even though every day without info delays the DVD further, and even though they're probably fully aware of that fact, imagine if they said something as vague as "yeah we don't know what's going on with our new DVD or at least we can't tell you right now but it is coming out and you'll get it sometime this year I guess" as an official announcement? Even worse, imagine if a day or two after that they got whatever green light they're waiting for and then be like "yeah uhm scratch that". They're just waiting for concrete info to tell us, very likely, and the fact they don't have it now is the source of my frustration (even though a couple of pages ago I posted something similar to the post I'm quoting).