Just pour it in on one end of the tank from the bucket. The fish will get out of the way. Just make sure to siphon out 1/4 of the tank water before as sand will displace water.
^ I always found just pouring it in a bad idea... makes the water more cloudy and takes longer to clear...
Where as if you put the sand in a container, then put said container in the water near the bottom of the tank and pour, it doesn't have as far to fall and therefore, less cloudy water...
if its been rinsed like he said it will clear quickly. I rather get that extra dust filtered out. No matter even if he poured it slowly it will still kick up.