Yes, that's what I did as well to connect 3 devices (TV, Apple TV and HP) from 2 RJ45.

It didn't work for me but my goal was a little different. Used a couple of boxes to pass hdmi over long distance via a direct ethernet cable. The first box, which has a power supply, powers the receiver box via the cable (PoE). I wanted to be able to connect the sending box to 4 different places and therefore put 4 cables. This is in the context of multiple network outlets at work to send the image to the projector. I don't know if it's to do with the power supply not going through (PoE) or the type of signal.
I returned it within 14 days free of charge.

Yes, this product should do the trick :)