Kekkai Sensen ep9, meaning of "playing it backwards in double-time/fast-forward"?
The vampire they were fighting was regenerating (I guess "playing it backwards" as in "reverting to a prior, unhurt state") quickly ("in double-time"). 

He had previously been severely injured by crashing into the skyscraper and by Klaus's attack. Note that about 30 seconds prior (in video time, not necessarily in-show time), he looked like this:



I think there's a kernel of a pun in here. Zapp says 逆再生の早回しかよ gyaku-saisei no hayamawashi ka yo. The word 再生 saisei has two meanings. One, "play" as in "to play a video". Two, "regenerate" or "come back to life". The prefixal 逆 gyaku means "the opposite of" or "reversed". So whereas a regular creature regenerating might be "coming back to life", an eldritch undead abomination like a vampire might instead be "coming back to life backwards" - gyaku-saisei, which is also the word you'd use for "to play a video backwards". 

I'm kind of reaching here, though; I'm not sure whether that was the intention.