Perhaps the first clue should have been the extremely convenient length of just 37 seconds — far shorter, it seems, than most amateur videos, and without awkward dialogue or fumbling. Then there was the convenient placement of the table and camera, and the suspiciously gentle door opening that still managed to push “Caitlin Heller” into a glass table full of candles. Will every fun thing on the Internet turn out to be a fake? Last week’s “twerking fail” was a pretty good one, though: It turned out to be a drawn-out prank by Jimmy Kimmel, who revealed on Monday night the girl was a stunt woman and the clip was a set-up from the start. At the moment the original video has 9,329,262 views, so as far as manufactured viral hits go, it sure worked.