Is this Slinger useful?

Chanced upon this on youtube, anyone tried this training aid before?

for a moment i tot u were referring to my shifu

doesn't your current ball flight already tell u how u are hitting it, what does this do besides give you the exact same feedback.

Yea.....wanted to say slinger useful then paused.

Great vid though

I think it may be useful forthose who doesnt have time to go range. Can use it indoor porvided uses plastic ball.