One of the things that mountain bikers struggle with a lot on rough trail is their position, or more specifically - Control over their position. Most mountain bikers' body positions are already out of balance before they enter every next trail feature, and that's where the problem begins.
There are three parts to position control that we need to be aware of: balance, stability, and posture.
Let's focus on the balance control part of position control for a moment. If you enter the start of a rough section of trail, like the one in the video, already out of control of your balance, then you're going to struggle trying to keep balanced until the trail eases. Why?
Because, when we enter any change in the trail already out of control of our balance, we will struggle to get back in control while the trail is still changing underneath us.
When we're out of balance we have to react and hold or brace ourselves to the bike, to try and stop us from losing balance even more. We will grip the bar tighter, stiffen our arms, and maybe even curl our back. We might even stiffen our legs and try to squeeze the saddle between our thighs.
We will also drop our eyes to the trouble we're having, which means we instantly start killing our ability to scan ahead and create the riding line we want. We might also grab the brakes in an effort to get back in control, but often that momentarily throws our body forward or sideways!