Yeah, only a day late, I know!
According to my pal Fred:
The mashup is actually Wax Audio’s follow-up to Maiden Goes to Hollywood, a different mashup they did of Relax and The Rhyme of the Ancient Mariner, on an all-Maiden mashup album called Number of the Bootz.
More info here: http://www.mashuptown.com/number_of_da_boots_album.html
Here are the original tracks: