If you take a look here you can find out a quicker way to deal with the the dam in Half-Life 2 (Thanks Monttis). Grab the movies also, in case you haven't done it yet.

Half-Life 2 Done Quick Movie (663.82MB)

Quake Done Quick Movie (165.81MB)

Doom 2 Done Quick Movie (134.98MB)

Half-Life Done Quick Movie (470.88MB)