After next series of experiments I found 3 approaches to start video record using usb-remote in Canon SX1. First two are based on standart 2.00H firmware, 3rd is based on SDM 1.85 firmware. Using standart 2.00H firmware you could create two following scripts (in 2 different files):
1. Video1.bas:
@title Video5 button while 1 wait_click 1 if is_key "remote" then click "video" wend end
Open the Notepad, insert the abovementioded string and save under name video1.bas
2. Video2.bas:
@title Video5 button while 1 wait_click 1 if is_key "remote" then press "video" wend end
Open the Notepad, insert the abovementioded string and save under name video2.bas
3. Video3.bas
:: use the script from the following url:
http://tech.groups.yahoo.com/group/StereoDataMaker/message/8212you can store formatting.
After experimenting with scripts #1 and #2 I noticed then the 1st script starts always but stops recording after 1-3 sec
if you did press the usb-starter's button more then 0.2-0.3 sec. If you pressed quickly then recording goes successfully.
Script #2 starts successfully at 100% cases and recording goes on, but in order to stop record you need stop script by "shoot" button, run it again and click usb-starter's button. It would be good to develop this script next in order to eliminate pressing "shoot" button twice.
I hope this info will be useful.