sorry for butting in,
as the talk for movie mode is going on - does CHDK support controlling the fps - can i set the move to 5fps for eg.
I can only tell my experiences with my old cameras and the SX100IS. The old A420 survives setting the framerate propcase, but the effect is not what one would expect. First, several routines in the firmware check the framerate, and only accept those that are supported (in the A420 this means 10, 15, 20, 30, 60 fps). Other values cause an assert. Setting something that the camera doesn't support (like 320x240, 10fps) cause a strange mode to appear (which is ~5fps and only uses the top of the sensor, so the picture is vertically distorted). Setting 30fps at 640x480 causes 30fps with upsampled(!) 640x480 picture (actual resolution is around 320x240). The setting takes effect on half-shoot. Recording is possible, and what the most fun is, it doesn't know the actual framerate (so at a setting of 640x480, 30fps the elapsed time display counts at triple speed (the 640x480 mode is 10fps originally). As this model doesn't have audio recording capability, I don't know what happens with that.
On the other hand, setting the framerate propcase on the SX100 causes the camera to stop responding after the first half-shoot (and I get a preview picture with vertical synch lost).
there does seem to be a propertycase for it(listed for Digic II not for IV on te propertycase wiki) but will it work if i set it to an arbitary value maybe 5fps or 7fps.
Try it, you'll get a crash. The setting should be changed elsewhere, but I haven't managed to find it yet. Any suggestions?

Seriously, it would be big help if somebody would find the part of the firmware that sets the sensor/ADC/DSP parameters...
IMO the time limit is probably due to heat
Maybe. But what would prevent the user to hit the record button again?
