Interesting discovery, well done spotting it. Based on what's going on here:
• Aside from weakening them briefly, the player shoots at the pods only when they're firing the 4-way diagonal lasers.
• At a certain point, shooting them when they fire the 4-way lasers gives 5k per tick. This is the same value for killing the enemy normally, which can't be a coincidence.
• The enemies only die when shot after the 4-way laser, suggesting the 4-way laser makes them briefly invulnerable when firing.
What I suspect is happening is this: the enemies can be lowered to 0 health and shot repeatedly when they're using the 4 way laser. If shot during the animation when at 0 health, the game fails to trigger the death animation because they're in a special attack animation, but the game incorrectly gives you points as though they've died with each hit, allowing you to milk tick points from them, with each tick equal to what you're supposed to get from killing them.
It appears this is the same thing you've concluded based on the footage, so we're in agreement this is probably what's happening. Should be testable easily enough for confirmation. If they can't be killed in their 4-way animation and give points per hit when doing so when the shots should kill them, that'll confirm it. I've found several other videos of the game where these tick points are triggering under these circumstances when shot at low health during the 4-way laser, so it's pretty safe to assume this is what's happening here.
What's not clear is:
• Which weapon is the most lucrative? Is green used deliberately because it's better for this milking than red is? I'm going to assume green is the best simply because someone who is aware of this trick would immediately think to try all 3 weapon types (as well as launching pods), but just in case red is better it's worth testing. Probably not though,
you can see I triggered the tick points with the red weapon on one of the pods in this 1CC and it wasn't worth much.
• Is there a timeout? The less lucrative video you posted seems to never stop firing so I don't think it's aware of the milk potential whereas the
first video link clearly knows what's up as it waits to pointblank the orbs. It does aggressively kill the second orb though on the second milk, so is that a mistake, or was it because the orbs were about to timeout?
Off the top of my head I think extends are pretty damn lucrative for the end-of-game score so I suspect it's not worth it (unlike Formation Armed F where final boss checkpoint milking gives you nearly 8 times what a normal 1CC would be worth).