Animation turns back where it started!

Hello!

So I downloaded some animations from the internet. When I play them in the scene, they turn back to where they started. I have to say that the empty object child-thing doesn't work for a reason.
Animation turns back where it started???

Please help.

Thanks!

I didn't find the right solution from the Internet.

References:
forum.usdfsanity.com/threads/animation-turns-back-where-it-started.518173/
Biometric Solution Video