Tobar has mentioned in the ESB:R thread that he actually saw the ROTJ clip at C5.

Tobar said:
Unfortunately, you can't tell from the youtube clips but the footage is actually kind of worn. It wasn't restored and looked quite aged.

If they had recreated the clip recently then surely it would have been restored? Vader walking down the corridor is definitely a cut shot from ROTJ as we have seen a few cut shots of that corridor plus it was seen in "Behind the Ewok". I don't think that the meditation shot was taken from an unused shot from ESB because it sure looks like the "super shiny" ROTJ helmet to me.

But also from this it looks like Lucasfilm aren't going to bother to restore the deleted scenes from the OT so god knows how bad the quality will be.