Quite frankly, the only decent results I got so far were with qt-recordmydesktop. glc is basically useless on x64 systems, and I couldn't find any other decent alternatives. If someone else knows of a better solution, I'm quite interested too.

I actually have my own project for providing a GUI for glc:
http://piga.tropicalwikis.com/wiki/Soul_Capture

This is the 1.0.0 version so not everything is as good as my own development one though. Waiting on getting some new hardware to add some requested options before I put out a new release.

Other than that, I would suggest you invest in understanding ffmpeg if you want the best in non-OpenGL specific screen capture.

Edit: Someone is apparently working on a new version of glc with new features such as PulseAudio support:
https://github.com/swick/glc2

Arch also sports a glc-pulseaudio-git branch. Doesn't change the fact that I (and I presume CzarnyNalesnik too) use an x64 system, where glc SEEMS to record, but can't playback.
If you had a hand in Soul Capture though, HOW THE HECK DO YOU PARSE A STEAM COMMAND LINE THROUGH THIS THING? :D
Seriously, I tried it (and apparently it's still installed from AUR), but never could get it to record a Killing Floor session. :/

Using the Steam launcher? Search me...

Can you try and bypass that and point it to the actual application you wish to run?

I did not even know it was in AUR though. :D

Actually, that depends. Games that do not rely on Steam too much work fine* by using a simple .sh indeed; others won't work that easily. Killing Floor for example, could technically be started by a .sh, but for experience, achievements and DLC, using a .sh means no steam, throwing you back to level 0 with 0 exp, no DLC, and no achievement unlocking (which of course in turn unlock more stuff in-game - skins, in this case).

* apart from the glc problems where it can record but not playback, and can only encode the video part of things. No sound at all, apparently things break when it comes to that. All x64-related from what I've read here and there.

Unfortunately when it comes to the x86 problems I can not offer you any help. Try contacting the guy working on the new glc and make sure he is aware of them though.

I might just put out a new Soul Capture release for New Years though since my hardware order keeps getting delayed.

I know, it was more to illustrate the fact that, under x86, everything /should/ be fine. ;)