Article continues below advertisementDonald Trump can't seem to catch a break from being trolled by critics. The president, 79, was mocked by commenters after the White House posted a video of him leading a countdown before Melania Trump, 55, lit up the National Christmas Tree on Thursday, December 4."Sort of impressed he was actually able to count down from 5," one person quipped, referencing the president's alleged cognitive decline.Article continues below advertisementSource: @whitehouse/instagramDonald Trump led a countdown before Melania Trump lit up the National Christmas Tree.