So we are taking a series of 30 second tests that are timed within a video, when we checked the time with a stop watch in the video the test was only taking 25 seconds in the video as compared to the timed 30 seconds during the actual test. This doesn't happen on all the videos, there appears to be some audio/video slight delay issues as well. Any idea what could be causing this, we are using pretty decent computers for this recording.