Walking While Talking
Walking while talking is a bug that allows Jak to enter the warp gate during the cutscene that plays after it's activated.
Technical
When a warp gate is active, Jak can stand nearby and get the "Press O to use" prompt to interact with it. When opening warp gates with cutscene triggers tied to them for the first time, there are 2 frames where the "Press O to use" prompt is active. The O button can be pressed during this time.
Frame 1
If the O button is pressed on the first frame, the warp menu opens as usual, but the NPC(s) will now be present in the area. If the menu is exited or if Jak warps away and returns, the cutscene triggered by the warp gate activation will play.
Frame 2
If the O button is pressed on the second frame, the cutscene will begin playing and the warp menu will appear. Jak can then warp to another location and then warp back and the cutscene will be skipped, minus the audio.