Looks like the hero 5 only has digital out, not analog which most drones use for live video. That said a board camera can be pretty cheap.

200mW camera video transmitter (runs off 3.2 to 5 volts) https://www.amazon.com/dp/B01MY3QSIE/ref=cm_sw_r_cp_apa_amK8zbGDV7GQD

Goggles with a built in video receiver battery included https://www.amazon.com/dp/B01AL0RM8G/ref=cm_sw_r_cp_apa_EoK8zbEZAYTDR

Flight controller + power module (voltage sensing, current sensing, 5v supply) + gps receiver/compass + gps mast + soft mount https://www.amazon.com/dp/B00SY3NMDM/ref=cm_sw_r_cp_apa_6tK8zb9E7AT58

Beyond that, if he already has a remote controller, a 5 channel receiver, and a battery that matches the power system he already has you are set.

the Flight controller + power module (voltage sensing, current sensing, 5v supply) + gps receiver/compass + gps mast + soft mount https://www.amazon.com/dp/B00SY3NMDM/ref=cm_sw_r_cp_apa_6tK8zb9E7AT58

has some bad reviews and i just wanted to ask if you think I should worry about it or not, since I don't know anything about this stuff.

If so, are there any other options around the same price that you know of? Thank you again for the help!