just did some calculations...
first a quick lesson on how broadcast TV is done..
http://www.sencore.com/newsletter/Jan02/JanNews/Understanding%20and%20Measuring%20Part%20I.htm
It quotes that for a NTSC horiz. res of 159 bits you would need 3 Mhz for video, needing a bandwidth of 4.2 Mhz.. (hey you look, you may understand better..)
now, taking the res to be 1920 x 1080, 3 colors, etc... adds up to 6,912,000 - and this is repeated 60 times a second!!
so the total number is 414,720,000 bits every second!!
thats about 415 MHz data rate...
NTSC is 525 lines, but this is interlaced, so is actually 262.5 lines, by say 160 wide - 3 colors makes it 126,000 bits, times 60 makes it 7,560,000... 7.5 Mhz data rate...
all you gotta do now, is figure out how to squeeze such a 'large' signal into the limited space as shown here...
http://www.ntia.doc.gov/osmhome/allochrt.html