Hi everyboby and thanks all for your comments.
The video has 25 fps. Each frame (1280x720) reached SL 15 in about 1 hour 45 min.
For the static scenes we used some renderings done before which, of course, had a different dimension (3200x1800).
The animated part of the video is 109 seconds (so it's about 2725 frames) and it took a month to render them with 6 computers calculating full time
(it was winter and we didn't need the heating!)
About the trick to speed up...well...if you have any suggestion you're welcome!
The only thing we did to reduce a bit the amount of calculation was to render a region where possible (eg. the kitchen animated part).
As kami rightly suppose, the fire and the animated images where added in post with AE.
To Mihai: the strange disappering...that's an LCD glass and what we wanted was to show how it changes but I agree with you: It simply doesn't work!