While there is some clever thinking at play here, unfortunately Captive is not something that will play well for me.

A few things to note when deciding.

1 - The cap is "dirty" after falling, meaning it is critical that the performer and not the spectator retrieve it. Afterward, it "could" be handed over for casual inspection, but I don't believe would stand-up to any real scrutiny.

While I typically stray away from allowing examination of props, this is already on the table and they will be inclined to reach for it, particularly in small groups. Audience management is a must, and I'd strongly recommend placing it under a cup as seen in the demo to help with this.

2 - The reset is not something that can be done within eyeshot of anyone. It is not complicated, and is pretty quick, but will require a degree of privacy to perform..

On the upside, if you can get past those negatives, the big positive is that the angles are very good.

Also worth noting is that mine came almost dry, to the point that the internals would need to be swapped out to use it.

The cap can't be examined (not before, not after the effect). After falling over there is likely something visible on the cap that shouldn't be there! Better perform in a dark environment.
Angles are a factor.
I'm not gonna use it.

Threw it away..idea was good but not workable or reliable