The new "Science of Doctor Who" show, as most of us know, contains a couple of segments with The Doctor and Brian Cox in. These segments were in-universe, and were seperate from the lecture part of the show.
Parodic doesn't have to mean comical. Though certainly that's a common definition, a parody is really something that imitates something else, but obviously falls short of being that something else. You can have an otherwise serious "parody of a wedding" simply by having no one present with the legal authority to perform it.
The Ultimate Guide sketch is a parody of a television episode because it cannot exist without the bit in the middle. The Doctor and Clara are shown to reflect upon the contents of the documentary that comprises the bulk of the show, so it's like a regular episode of Doctor Who, but it's not a regular episode. The plot resolution comes through the conveyance of non-fictional information.
A more recent example of the kind of thing we've disqualified in this regard is the National Television Awards Sketch 2011. Because the "narrative" of that sketch depends on believing the Doctor was somehow involved with the non-fictional awards show itself, we obviously can't include it, because that would logically mean that everyone who was in that awards show was a part of the DWU. In the same way, we'd have to believe that Tovey's narration, the actors who played DWU characters, and every other interviewee were themselves a part of the DWU in order to admit the sketch.
My main objection here is that I see no difference between counting Death Is the Only Answer as valid as well as this Night with the Stars mini-episode. Both are mini-in-universe "skits" compacted into out-of-universe sources. Both have their own pages, and are separated from their respective out-of-universe documentaries. The confusion seems to come down the the fact that DItOA is extremely random and has nothing to do with the Documentary it's featured in, while NwtS is well written and relates to the subject at hand.