szrk's "use-glitch" run is here:

There is a comment on the video that reads as follows:

"This is not a glitch. (I think developers done this intentionally. May be to replay KINGS FIELD 2 US version like Diablo games). Both versions (US version and Jap version) have this trick. You need just load your game from previous gameplay in the end of the game and then you need just sell all items that you want to Ed Edmund (Ed Edmund - that NPC that sells items in this video) and kill character without having Dragon crystals.
For example: if you sell to Ed Edmund Ichrius crown and broken moonlight sword or any other item\equipment and then if you kill yours character without having any Dragon crystal, then game will be started from begining with character at level 1 and 0 exp, and Ed Edmund will sell same items that you sell him before, in the same quantity. Because of this trick it is possible to have 99 crystal flasks or even 99 Excellectors."

My disc should be arriving in the post soon and I will do some testing on this so we can get the categories squared away. I plan on running this game relatively soon.

It seems like in szsk's run, he obtains the broken Moonlight Sword despite not selling it to Ed in the first place. I'm thinking that there may be a system for NG+, but this particular interaction is the "JP-only" glitch part.

Alright! I finally solved it. There's no glitch - szsk's run was created by selling items before the beginning of the video, just like kerotto's (ケロット). So the Youtube commenter was right! Here is the evidence:

"Advance preparation
Sold Moonlight Sword (Ori), Crown of Isarius, Corridor Key x 3, Rhodom Key x 2 to Ed, died without a rhinoceros fruit, became game over, and restarted. Time attack starts from here."

taken from szsk's website: http:/​/​bmky.​net/​yarikomi/​kf3_nta/​chart/​

I've set up the categories properly now.

Clarification: the fact that you can still buy these items after dying might be (probably is) an oversight, and thus a glitch. Unclear.