Is it possible to dedicate a core to do something? For an example, for a Quad-Core processor, 2 cores for the game, 1 core for the recording of the game and the other core for everything else. Is it possible?
yes it is. Press ctrl+alt+del and load the task manager. Switch to the processes tab, and select the processes you want to change. Right click it and chose 'Set Affinity'.
So that dedicates a process to a core. Does it also allow me to dedicate a core to a few more processes?
you can dedicate as many processes to a single core as you like, but bear in mind that they are all competing for the resources of that one core.