Not sure what's going on? Are you having trouble recording demos, playing demos or both?
For Playing demos I use Quake Live Demo tools.. It's great..
For recording a demo I use a script in my auto exec. As auto record demo in QL is flakey..
Simply change the bind s at lower left to whatever key you want..And you can start and stop a demo easily in game without having to use the console.
set start "record; set demotoggle vstr stop"
set stop "stoprecord; set demotoggle vstr start"
set demotoggle "vstr start"
bind s "vstr demotoggle"