I think you are mis-hearing it. I can't verify because the video won't play for me.
I think you're mishearing it, or the てある is being elided into たる in the same way ている can be elided into てる. Like I said, I can't verify, though.
The only time I know when you can precede ある with the plain past form of a verb is when you're using ある to mean "some" instead of as an actual verb. See any number of examples here:
“たある”の検索結果（98 件）：英辞郎 on the WEB：スペースアルク