A few seconds after exiting, this skydiver felt something hitting his leg — it was his main canopy in the d-bag! He knew his pilot chute was still in the BOC and realized he had a horseshoe malfunction, so he tried throwing his pilot chute but it wrapped around his leg. He kept attempting to clear the pilot chute — even removing his shoe to see if it would help — until his audible altimeter told him he was at 5,000 ft. He then went through his emergency procedures by cutting away and pulling his reserve. Fortunately, there was no entanglement between main and reserve and he was under canopy by 3,000 ft.
A horseshoe malfunction (and losing a shoe) makes for a very "exciting" 187th jump. Great job on keeping calm, trying to clear the wrap and following emergency procedures. Well done.
Everything that we see in this video is secondary to the fact that this jumper's main pin became dislodged. He noted that he believes it may have happened upon exit; he may have bumped up against the door of the aircraft.
The biggest takeaway here is to protect your pin, flaps and handles. Before you get on the plane, during the climb to altitude, and then immediately before and during exit, it's critical that jumpers remain aware that they're not rubbing their container against anything that could snag a handle or pop a pin.
The jumper said he did his gear checks on the ground and checked himself immediately before exit, including touching his main pin with his hand. However, he didn't get a buddy check in the plane. As such, it's possible he may not have realized that the pin had been bumped and become unseated while he was moving around. Having another jumper visually inspect his container may have prevented this incident.
When fully seated, a closing pin should have enough tension on it to prevent it from being easily dislodged. This issue combines a variety of factors: closing loop length, pack job density, proper container-to-canopy sizing, etc. This is something that should be taken into consideration every time a canopy is packed. If that closing pin slides around very easily because there's not enough tension, one of those aforementioned factors needs to be corrected.
One thing that immediately stood out to us was how the jumper never checks a visual altimeter. However, he was obviously aware of his altitude given that he fought the malfunction down to his pull altitude and then executed his emergency procedures promptly enough to be under canopy by around 3,000 feet. The jumper noted that he uses two audible altimeters and relied on them. However, there is a debate about whether relying on two audibles and not checking a visual is an acceptable practice.
This jumper did an excellent job remaining calm. The fact that he took the time to think "Hm... maybe I should try ditching my shoe..." was awesome. By remaining calm, thinking the incident through, and knowing to listen for his audible to go off, he did a good job maximizing the chances that he would walk away from this incident.