Interesting that it contained 3d content considering the BBC have stopped their 3d channel due to lack of interest. People would rather have more 1080p channels than 3d it was reported. I did watch the DOTD (under duress) and the 'in the picture' scene did seem to spring out at you in an almost 3d sort of way, despite us not having a 3d tv. Rather stay with 1080 with surround sound for now and wait for the 4k stuff to come down in price. Talking of hd, because of the 50th Doctor Who anniversary my cable company are offering loads of DW on demand content, with some of the old 60's B&W stuff but the early 70's colour stuff too. What was amazing to watch was the old 1973 The Three Doctors episode in 625 line colour upscaled to HD. It was really clear and relatively high resolution for the technology at the time. Almost on a par with the 720 so called hd. It certainly never looked like than when I watched it on our old colour tv when I was a very small kid that's for sure.
The 625 line PAL colour signal was actually very good quality, as you note, and shows preserved from that time were recorded on 2" quadruplex video recorders, the best available analog technology. I believe this remained the professional standard until digital recording came along. The difference in watching those shows now is that flat screen TVs have far better resolution than the old CRT sets, and there are no problems with convergence (which caused colour fringing at the edges and corners of the CRT screen), and other unwanted effects associated with analog transmission and viewing.
To quote the Goon Show: "Are you the Chancellor of the Exchequer?" "No - oh, the Chancellor of the Exchequer! Oh well, I can understand because I've often been mistaken." "For the Chancellor?" "No, I've just often been mistaken, that's all."
To the question of whether or not 3D adds anything to this movie, well, the answer is yes. The subject of this feature is something in 3D that shouldn't be for its time (or ours), and it is an object that is important and remarkable. If you see this, 3D is really the way to go. I'm not a 3D fan. I don't even own a flatscreen, except for the 15" 720P that sits on my desk.
Spoiler alert??? The webisode link was posted in message #9 above...and you repeated the link in your quote. ...or were you referring to the comment that the Warrior Doctor regenerates into Eccleston? Pure speculation on my part.
The webisode is merely a promo for the movie. Nothing more, nothing less. Spoiler? No, just an advertisement and teaser for the movie/feature episode. It sets the viewer up for the movie. It was very heavily promoted for fans of DW to reel them in to see the 50th year special episode. It does set up a small story to steer the series viewer in a midset for the special. In my view, as a fan for 40 years, it is a necessary must see before the movie. Moffet wanted it that way.