Source Recorder is reliable, plus it's not a real performance hit (as opposed to Fraps).
Record a demo (ex: record your_demo_name [in console]) of the gameplay, then simply go back & use this command line in the console: host_framerate 30;startmovie your_movie;playdemo your_demo_name
The only problem you have to solve from there is how to compile the output .tga files and the .wav file into a single file. You can easily use Sony Vegas (download the trial, what you do beyond there is between your computer and you) to compile the video (there's a tutorial @ http://forums.facepunchstudios.com/showthread.php?t=148196) and you're set.
I use the above method for every Source-based video I wish to make. It's not for everyone, but it is the most reliable way.
Just so you can see how good it is, here's a video I made the other day to show something I had done the first time I had played through Half-Life 2 (mind you, I used Windows Movie Maker to compress, everything else done in Sony Vegas): http://www.drkstudios.net/drkpwn3r/HL2 Jump.wmv
