First, the video signals pass through {HEAD ~ the video operational amplifier} and video buffer 312 and {TAIL ~ the video switch circuit} 306 
First , the video signals pass through { HEAD ~ the video operational amplifier } and video buffer 312 and { TAIL ~ the video switch circuit } 306
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH