As a result, {HEAD ~ the child frame video} can be switched freely between display and {TAIL ~ non display} within the range of the displayable time 
As a result , { HEAD ~ the child frame video } can be switched freely between display and { TAIL ~ non display } within the range of the displayable time
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH