http://www.buzzerbeater.com/match/35877339/reportmatch.aspx?realTime=2739
Definitely not a matchviewer problem, because he shoots the free throw, is recorded the point and then leaves the court.
He should not have been able to substitute unless he was injured.
is that really forbidden in the nba(as stated college and fba it is allowed), i didn't reached the rules now but i think as long as he hit he is allowed to substitute.
but this substitution takes also place (here) after a missed extra free throw and in this case the game isn't stopped and the shooter is not allowed to leave for sure.
So it isn't only the fault of displaying the substituition before the shot.