(Reuters) - The young man in the black woollen ski hat is nervous. He pauses repeatedly to catch his breath and remember the short speech he has prepared.But when he speaks, he addresses Belarusian President Alexander Lukashenko in a firm, clear voice. In his left hand, he holds a red and white flag, the symbol of the protest movement against the veteran president. “You must announce your departure, you must halt violence and you must release all political prisoners,” says the young factory worker, who gives his name as Viktor Mankevich. A video here posted on Twitter on Wednesday shows Mankevich making his lonely protest after climbing a ladder to reach a narrow platform near the top of a factory chimney.