With LiveSplit I timed it to 5:15:01, but it looks like the end split was very early even though I remember that I split on cutscene start. The youtube video is frame counted at 60000/1001 frames per seconds, so that time should be correct.

Child 1 could probably be 1:30 faster if optimal, then Child 2 I lost 1 minute, Forest temple 30 seconds maybe, Ganon's castle 1 minute. Probably some small mistakes here and there that add up to a minute. Sub 5:10 probably possible in the future.