Okay my "quick video" turned out to not be so quick. Also I meant to note that this is applicable to X-ray and gamma radiation mainly as they mostly don't interact in air so they spread in the way I described. Beta and alpha have other considerations I might get into in another video.
The detector used is the Better Geiger S2, you can get it at www.bettergeiger.com
Please comment to share your thoughts on this video and let me know what I should do next.