I suspect you are confusing 2 different devices. A antenna is pretty simple. You likely could use any directional antenna rated for 5g and it would work. Ones for 5.8g most likely exist but likely cost lots more since there is not a lot of demand. I would look at something in the 15db range 5g antenna for WiFi.
You much larger issues is some magic device that can some how hook to a phone and some how receive video in the proper format. This will depend greatly on the application you are using. You will likely have to buy devices compatible with the service you are using. This is why WiFi for wireless works so well it is standardized but when you talk wireless video there are many competing standards of which are not compatible.
So find some device that works and has external antenna connections and then buy a direction antenna to extend the range. Be aware you are likely going to have to buy costly mircowave cable. These antenna need to be place outdoors with clear line of sight. Since the device must connect to your phone and the antenna you are stuck using cable between the device and the antenna because you are limited to 15 ft by usb cables.