There are videos of Palestinians being shot in the head, yes (NSFL links below)

Here's a video from last year of an elderly man carrying a white flag being shot in the head: https://www.wgbh.org/tv-shows/newshour/clip/war-in-the-holy-... (this news site removed the moment of impact but I'm sure you can still find it)

Here's a video of IDF in the West Bank head-shotting an unarmed elderly man who posed no threat: https://en.wikipedia.org/wiki/Killing_of_David_Ben_Avraham In this one, the man had converted to Judaism after feeling an affinity to the religion due to his grandfather saving the lives of more than 10 Jews during the 1929 Hebron massacre. His Aliyah request was denied, and he was executed while attempting to visit a settlement (by invitation) for Torah study

This one from 2018 was widely circulated (this victim was shot in the leg, although based on the IDF recording here many had assumed this was also a headshot): https://www.theguardian.com/world/2018/apr/10/video-appears-...

Here's a very detailed report on 15 aid workers in Gaza being executed at point blank range and dumped into a mass grave last year: https://www.dropsitenews.com/p/israeli-soldiers-tel-sultan-g...

These are just ones that come to mind as some of the most brutal ones, but there are many, many more videos of the IDF executing unarmed Palestinians who are posing no threat by head-shot. And for every one we see there are likely 4 or 5 more which we don't see because they weren't independently recorded.