The first scene is cut and splice to make what was supposed to be the celebration scene at the end of ROTJ (using a variety of sources). Not pretty mind you, but interesting (though of course now we'll get it for real in the new box set anyway, but it may differ to the one now).
Same with the next part which is an intro which is hugely missing in the cut of A new Hope we've seen, using bad deleted footage, screentests etc. in a way that makes it interesting to see (if even in a shady way) and hear what we missed and think about they way it was originally intended from scripts.