While we don't normally think of water as "sticky", it actually does have some "stick" to it. The molecules of the water are attracted to each other and form a kind of elastic layer/barrier that allows the strider to float. It's also what keeps bubbles and water droplets together in a spherical shape...and is one of the physical properties of soap that helps soap clean.
Soap is a "surfactant" which is a contraction of "surface active agent." Surfactants are amphiphilic, meaning they contain both hydrophobic (water repelling) parts and hydrophilic (water attracting) parts. Essentially, it acts to make the water "wetter" - breaking the surface tension of the water, and allowing the water to clean the dirt and/or oil better. This simple (and fun I might add) experiment demonstrates how this works.
Take a piece of card stock or poster board and cut it into a boat shape like this, with a small notch cut out of the rear.