Minimal circuity for a simplex video transmiter?
If you want the ballpark value of a "good" free-space optical link, "Data rates of over 100 Mbit/s can be easily achieved" from the wikipedia page Free-space optical communication. 

Using a visible light laser and receiver will probably work rather well. Though, to get any good data rates, you probably need to spend quite a lot of time on your design, or buy an already implemented laser receiving-optics + amplifier + demodulator module.