Using half duplex, that is sending then recieving quickly makes it feel like you are sending and recieving at the same time but you are not.
Imagin send for 10ms and recieve for 10ms and you think it is doing it at the same time butit is not.
Sending video use a specific video transmitter notthearduino, it is not fast enough.
aha ok then yes your right
so about the video transmitter i will do search for but do you may know some module that is world wide and might find it anywhere and not expensive ? and for the camera can i still use the ov7670 with fifo can still be for the job ? does the cam matters or not ?