Apart from the fact that you would either need a license to transmit the video on rf unless you used an unlicenced MST band such as 2.4 Ghz which would still be a majour headache over ten miles, you are talking serious ERP unless using a highly directional antena the encryption/decryption could only be achievable with dedicated hardware such as the devices I design.If you gave me some sort of idea of how secure the encryption needs to be I could give you an idea of how to achieve the encryption/decryption.
it is remarkable that non of the things you want to do are achieveable with a 8052.You must win some kind of prize.