Check out a cool fan-trailer for The Flashpoint Paradox featuring footage from the DC TV universe, DC TV and other sources put together by the UltraSargent YouTube channel.
Flashpoint was the DC comic book event that precended their 2011 New 52 relaunch. It was a pretty awesome series that saw The Flash change history and the DCU completely (for better or worse depending how you look at it).
The last scene in the above trailer features a Batman Vs. Superman cameo spoiler.
I'll also include an explanation below for some of the footage (watch the trailer first if you are unfamiliar with the DC Comics Flashpoint storyline).
Jeffrey Dean Morgan's Comedian Watchmen role is used as the footage for Thomas Wayne. In Flashpoint, a young Bruce Wayne is the one that gets killed, and Thomas Wayne takes up the Batman mantle, which is a gun-toting version of the vigilante. He battles his arch-nemesis The Joker -- his wife, Martha Wayne.