In movies, sometimes the character will put an ear to the ground and then hear people moving a long ways away example.
Does this actually work in the wild at all or is it just insufficient for anything short of a
horde of orcs herd of buffalo?
If there is a herd of buffalo you will hear them sooner by listening at the ground, then in the air.
BUT only if there is lot of them, making a large impact. A single animal or even a few is unlikely to have enough energy to transfer sound any distance in the earth.
In a solid, the particles are even closer together and linked by chemical bonds so the wave travels even faster than it does in either liquid or air, but you need quite a lot of energy to start the wave at the beginning. source (sciencelearn.org)
Related sister site question Do trackers hold their ears to the ground?