have taken to the streets of bangkok for the fourth day in a row demanding political reform. the rallies took place in defiance of a government ban on gatherings there. the protesters, who are mostly young people, want power to move away from the military and the monarchy. from bangkok, jonathan head sent this report. friday night in downtown bangkok. police advance on a political rally. screaming. never mind it was mostly students, school children and commuters dropping in on their way home. they got the full treatment. yelling. water cannon laced with blue dye and tear gas. it hasn't put them off though. they gathered again this weekend, demanding notjust a change of government, but a radical overhaul of the political establishment which has ruled this country throughout