The first video deals with the more personal ways to hurt people, places, and things in Red Faction: Guerrilla, including the assault rifle and the powered sledgehammer - my personal favorite. The second clip deals with the more explosive ways to deal with enemy nouns in the game - proximity mines and the remote mining charge, which is essentially a sticky grenade with a remote. I'd imagine that would be great fun in multiplayer, sticking one to an enemy and then simply...waiting.
That's exactly why I suck at multiplayer shooters. I spend far too much time trying to show the other team a good time.