Regarding the videos, Jon has average, at best, flexibility. Though I’ve seen him squat with his feet a little wider, in this video, if you look at his squat, his feet are too close together. Therefore, his hips are posterior. The limiting factor is his hip joints, not his ankles. Ideally, the hips would be between the ankles, which would allow for a more upright torso keeping the shoulders over the ankles. This eliminates the excessive forward lean which then requires increased shoulder mobility to move the bar rearward to the shoulders so a snatch may be saved.
In a perfect scenario, which most never achieve, if you looked at a lifter in the squat snatch position from the side, everything would be in a perpendicular plane, the bar, shoulders, hips and ankles. Most have the hips posterior to the ankles, shoulders anterior to the hips and bar posterior to the shoulders. All to varying degrees, but it is the hips that require the compensations above for balance purposes.
I disagree with Glenn regarding the value of the ankle flexibility exercise shown. It’s fine for what it is, but usually the problem is the boney architecture of the pelvis, acetabular angle, length and alignment of the femoral neck. There are some simple tests that evaluate retro/ante version of the hips, but CT is the best way to evaluate it.