Are you sure your elbow is not locking out straight on your push just prior to release? It may be my tired eyes, but it looks like your elbow relaxes to a more natural position only after the release.
Don't take anything I'm saying as gospel, but I'll share a technique taught to me by my Granddad years ago on obtaining a natural elbow bend and a natural cant for shooting a longbow. It has worked for me for over thirty years but it is more based on a swing style draw.
With empty hands, stand at attention while directly facing your target. Have your open hands flat against your pant seams with your arms straight and with your elbows pulled tight against your sides. You will notice that it requires muscle tension to keep your elbows in and your hands flat. Now, completely relax your arms and shoulders, but keep your thumbs against your pant seams. You'll notice that when you relax, your elbows and the knife edge of your hands will pull away from your sides giving you a slight bend at the elbows. This is a natural position without any muscle tension.
From this natural position, raise(swing) your arm(s) directly straight forward up to shoulder level. Do not bring your hand(s) directly under your eye but keep them straight forward in front of you so that you would maintain the same natural shoulder width separation between your left and right arms/hands. From this position, you will notice that your elbow has a natural bend and your hand will be in a perfect low wrist position with a natural cant. This position uses all natural bone support with no added muscle tension.
Now, from this position with your bow arm/hand up at shoulder level, pivot on your bow side foot and rotate into a shooting stance while holding your bow arm up in position. At this point your bow arm is in the most natural position possible for your body structure. Just like in good firearms marksmanship, you're using tension free bone support. You can now lower your bow arm down to your side and swing it back up while maintaining this natural arm/elbow/hand position. This position is very forgiving on your elbow and shoulder, especially with heavy longbows. I was taught to master the longbow by naturally bringing it to me, not to become a slave to the longbow by twisting myself to it.
Going through all the steps above was only intended as a learning stage to find this arm position. Once you have the feel for it, it comes naturally without thought from any position you shoot. I've used it now for over three decades shooting longbows and it has served me well. I'm of the opinion that any operator added tension or Popeye torque to the shoulder/elbow area when shooting any weight on a longbow is a shortcut to injury. If you ever look at high speed film, you'll see a good deal of energy being directed back into the bow hand/arm. In a neutral position, you are using mostly big bone/muscle structure to absorb that shock. With the added bad tension, you are directing a good deal of shock into weaker areas that may become prone to damage.
Good Luck,
Daddy Bear