You mean demo_jump doesn't work ? demo_jump -00:05 and so on works fine here.
On my movie config I have those binds also :
bind F1 "demo_capture start 120 demo"
bind F2 "demo_capture stop"
bind KP_HOME "demo_setspeed 70"
bind KP_UPARROW "demo_setspeed 80"
bind KP_PGUP "demo_setspeed 100"
bind KP_LEFTARROW "demo_setspeed 40"
bind KP_5 "demo_setspeed 50"
bind KP_RIGHTARROW "demo_setspeed 60"
bind KP_END "demo_setspeed 10"
bind KP_DOWNARROW "demo_setspeed 20"
bind KP_PGDN "demo_setspeed 30"
bind KP_INS "demo_setspeed 00"
You can find my movie config
here.
If these commands doesn't work, it might be a problem with the way demos are recorded on megaTF...