Donald Trumpshooter Thomas Matthew Crooks was caught on video lurking in the background of the Pennsylvania rally at least an hour before he shot at the former president. RadarOnline.com can reveal the video of Crooks was recorded by an event attendee and showed a man matching Crooks’ description pacing the perimeter, near the building he later climbed to fire at Trump. It’s been reported the footage, which was recorded on the man’s phone, was obtained by WTAE-TV Pittsburgh. The Trump supporter who took the film said he did so because he was trying to capture the size of the crowd at the rally…