I don't know if it's a looped "dirt & scratches" effect but about the resolution: the cantina scene, aunt Beru, old woman on tatooine, and Luke meeting Biggs before the battle is all in HD for real.
Strange thing I noticed about "the search for R2-D2" scene is that it looks like it was upscaled from DVD resolution without being deinterlaced or something, as can be seen in this frame: http://img685.imageshack.us/img685/9518/swdeleted02m2tssnapshot.png
EDIT: Check this frame from the ROTJ deleted scene also: http://img23.imageshack.us/img23/8915/rotjdeleted02m2tssnapsh.png
Looks like they forgot deinterlacing again.