Im trying to record some qw to avi and whenever I enable demo_capture_mp3 "1" and then start recording it gives me the error saying no ACM filter found? I've made sure I've installed ACM so is this a common problem and how can I fix it?
If not Ill have to use virtuadub to re-encode the audio after.
Thanks in advance

Sadly this is a very common problem, actually I haven't heard about anyone who would be able to get mp3 compression working.

TBH it's better to record as PCM then transcode to MP3 later if you are going to mix music & game sounds. You COULD append MP3 audio clips if you don't plan on any music, but it will compress more efficiently working with the whole audio stream rather than joining MP3's