The video above is sped up; slime molds do move, but they move slowly (or quickly for little organisms, take your pick). 1 millimeter per hour is not very fast, but it is something; some lucky slime molds can win marathons at 2 cm per hour. Most fungi do not move at all.
Unless you happen to be on 'shrooms. Then you can tell the purple unicorn in your bedroom that we said hi.
Slime molds are not molds. They are...themselves (the ones visible to the naked eye are myxomycetes). Nobody really knows where to put them; they used to be fungi, then were moved into their own taxonomic category. When all is said and done, they will still probably be classified as eccentric fungi or protists (which is sort of a catch-all category).
Or discarded bubble gum. There's another one called "dog vomit."
Slime molds start life as amoeboid, single-celled organisms. They eat bacteria, so, like most fungi, they can often be found on decaying logs. When they encounter an individual of the opposite mating type (sorry, not all tiny critters are as gay as rotifers), they form zygotes and soon become long, sticky plasmodia.
The plasmodia stage is what gives slime molds their name. In this stage, slimy, multinucleic threads start feeding like crazy. technically, this huge mass is a single cell with many nuclei. Eventually, the slimy mass forms fruiting bodies similar to larger versions of the sporangia found on regular molds. The cycle begins anew after that.
Not remotely like Japanese porn.
Still not creeped out? Slime mold feeding bodies can get several meters in diameter (and they are not even the largest unicellular organisms). They can pick the shortest road out of a maze despite lacking a nervous system, much less a brain. In the future, they might even evolve into something like this:
If you're slightly less optimistic, they may also evolve into giant blobs.
(P.S. - Like my fish? :D)