The random access memory provides realtime access for recording and playing back {HEAD ~ video} from and to {TAIL ~ a video source} 
to
The random access memory provides realtime access for recording and playing back { HEAD ~ video } from and to { TAIL ~ a video source }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL