By Moira Warburton and Doina Chiacu WASHINGTON (Reuters) – U.S. House Speaker Nancy Pelosi, Senate Majority Leader Chuck Schumer and other top lawmakers urgently dialed military officials and White House staff seeking help during the Jan. 6, 2021, assault on the Capitol by Donald Trump supporters, video shown on Thursday revealed. At what is likely its last hearing on the deadly attack, the House of Representatives Select Committee aired the previously unseen video that showed the fear gripping the Capitol as rioters stormed the building. Video showed Pelosi and Schumer, top Senate Republican …