I got around to testing this glitch today... good thing LagDotCom was around on IRC to explain everything to me.
Here is a link to my Pocket Monsters Green recording done under KiGB:
Pocket Monsters - Green Version (J) (V1.0) - dokokashira.inp. Of course, the
original vid and LagDotCom's
AVI recording under BGB are also legit, but I figure some people might prefer an input recording for complete proof of the glitch.
So I've finally come to understand that the main reason we don't yet have a TAS using this trick is VBA's improper emulation. The trick has been shown to work on TGB Dual, BGB, KiGB, possibly some other emulators, and the real hardware. To come to understand and use this trick in a TAS, I see only two possibilities:
(1) Fix this emulation bug in VBA.
(2) Implement rerecording in some emulator that is more faithful to the hardware, such as BGB.
I'd say (2) seems pretty impractical as most of the good GameBoy emulators are not open source. (1) could be done by someone who is up for the challenge, but seems pretty hard to me. It would require not only stepping through the disassembly in an emulator where the glitch works, but also comparing that to what's going on in VBA. The key discrepancy might not occur at the time of teleportation, but rather much further back. Maybe someone else has some better ideas.
Regarding the importance of this bug, I don't think this sort of warping is necessarily limited to Pocket Monsters - Green Version (J) (V1.0) and Pocket Monsters - Red Version (J) (V1.0). Indeed, in these videos the route is initiated by using some glitch with the select button on items to cause corrupted data, and the select bug was apparently fixed in subsequent games including all the (U) ones. However, the warping itself is caused by the corrupted data. This same sort of corruption (your first pokemon turning into a Charizard, getting an overflowed life bar after leveling up) can be obtained using other known methods (for example, capturing various glitched pokemon on the Cinnabar coast or using trainer-fly).
That's my take on things. Hopefully I've offered some insight that hasn't already been said
here.