The Demon's Souls servers are officially shut down as of February 2018. For a temporary workaround to access accurate IGTIn-Game Time, please see this Reddit thread!
The Seal Skip can be used to skip getting the Key to the Seal from Ingward and lowering the water in New Londo Ruins by using a Save & Quit and Fall Control to get to the Four Kings. It was discovered by Fed981 in December 2014.
It is possible to perform it without Fall Control, though the timing is more precise. From there it is possible to fall into the Abyss via an OoBOut of Bounds path, see the video by Fed981.