In the precision infrared video data acquisition systems based on TVP5147 and FPGA chips, the video signals are captured by using the Horizontal sync signal (HS), Vertical sync signal (VS), Odd/even field indicator signal (FID) and Active video indicator signal (AVID). This may generally cause the video capture part and video display part to be unable to use the same clock pulse signal, so that video capturing and video displaying can not be synchronized when the video is switched. A method for extracting video signals and clock signals by decoding VPO video data stream is presented. Since the video capture part and video display part can use the same reference clock signal, the problem that capturing and displaying are not synchronized when the video is switched is solved. The method is verified in our self-developed video capture system and good effectiveness is exhibited.