Just a quick note about your riding style -
looks like you are really mashing the pedals down, causing the left-right waggle of the bars/bike.
Try riding slower for a bit, with a smoother circular motion of your feet.
No need to "pull" up (can't remember if you are clipped in), just release the weight on the rising leg.
Try to push over the top, and scrape the bottom (like there is crap on your shoe)
again - work on this at a slow speed, look farther out into the distance, not over the front tire,
and see if the bars become more steady/wheel tracks straighter. this will help with efficiency.
and you cut the trail at 7:59 - 1 6MR demerit!
PS - you own the thread, so you should be able to change the title.