I think that only one device can see the video. But here is how to link two devices, it's easy.
Just install the app (or, install the Solo app on one device and Tower on another device), and then connect to Sololink_xxxx just as you normally would. Be sure to enter the WiFi password for Solo (don't forget to change the default password), and be sure that both devices have connected to the Sololink_xxxx access point.
From there it's easy. The first device connected will get the video. I haven't seen any video on the second connected device, but the second device can see flight information, etc.