lol. This does not work on all wake-ups, but many. It affects different characters, well, differently. If you read my youtube description, it's often safer to use U4+slide instead of U4+parry. Varies depending on your opponent.
The parry glitch was discovered by someone else a long time ago. It happens when your opponent hits an ice bomb and parry at the same time. Instead, I'm throwing in U4(cancel)+parry to make it safer against wake-up attacks... but like I said U4(cancel)+slide is often safer.
I'm just surprised you can hit your opponent OTG after the parry glitch. I don't know if that was known before.