This allows a user to download {TAIL ~ only a difference} between {HEAD ~ quality levels}, saving time and resources, rather than downloading the entire multimedia stream afresh 
This allows a user to download { TAIL ~ only a difference } between { HEAD ~ quality levels } , saving time and resources , rather than downloading the entire multimedia stream afresh
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH