Why is water coming out of the icebreaker?
At the very beginning of that video, it isn't breaking any ice, it's just pushing the small fragments aside as it moves forward. If you watched more of the same video, you will see that it does shoot water.

It is equipped with what is known as a snow-melting water-sprinkler (融雪用散水装置). It is not a device to lift the ship up, but a device to melt snow. It shoots out pumped-up sea water to melt the snow on top of the the ice, reducing friction (and cushioning) between the ice and the ship, making it easier for the ship to break the ice.

Some references I used.
JMSDF Shirase page (JP)
Kamome propeller company, makers of the sprinkling system