The video is interesting for a few reasons; first namely that like the Wrath of Magnus video it is told in the first person (one can only assume it's Abaddon at this stage).
Secondly for this line: "...The Emperor's angels have returned, recast from shame and shadow, reborn in black and gold..."! There's a few ways to take this - black and gold you would think refers to the Black Legion, so does that mean that the Black Legion are coming back, OR when he refers to "Emperor's angels" does he mean The Fallen (previously Terran-born Dark Angels, the Emperor's first legion) have joined the Black Legion and now return to avenge their exile?
We're running on a theory here that the Dark Angels will be playing a part in the upcoming Wrath of Magnus story arc, having recently been infultrated by Tzeentch, so The Fallen turning up in some capacity works into that pretty well. Our hope is that The Fallen will infact find their way back into the ranks of the Dark Angels in some way (if they aren't already as the Consecrators Space Marine Chapter) especially since one of the themes of Magnus' return is reuniting his detractors.
So what are your thoughts? Cadia is the next battlefield, so who are the players??