I see now, hero. I didn't want to go into much detail in the YouTube description, but just mentioning the minimal requirements for it to work.
The reason why Varia MUST be de-equipped is because you need to fool the game engine thinking you still have enough energy for another MB-beam attack (which you would indeed have if Varia was equipped) so that it allows you to stand up again. As Kej said, the check for the stand up seems to happen before MB's beam is even finished, so it fails to realize that your energy would be too low after it. That way your low energy finally triggers MB to make the Metroid joining beam in the last moment, but since the stand up possibility gets decided way before the beam attack, you can just do so, despite that it shouldn't be possible in this conditions.
It would be great if a solution exists to make this glitch work with both suits on, but thinking realistic about all the facts mentioned before, it just can't work out.
Good luck to try though, maybe you can indeed come with something completely unexpected, as improbable as it may be.
The reason why Varia MUST be de-equipped is because you need to fool the game engine thinking you still have enough energy for another MB-beam attack (which you would indeed have if Varia was equipped) so that it allows you to stand up again. As Kej said, the check for the stand up seems to happen before MB's beam is even finished, so it fails to realize that your energy would be too low after it. That way your low energy finally triggers MB to make the Metroid joining beam in the last moment, but since the stand up possibility gets decided way before the beam attack, you can just do so, despite that it shouldn't be possible in this conditions.
It would be great if a solution exists to make this glitch work with both suits on, but thinking realistic about all the facts mentioned before, it just can't work out.
Good luck to try though, maybe you can indeed come with something completely unexpected, as improbable as it may be.