TobbuudVouri himself said that he has this effect due to missing texturesthat could actually make sense. if you look at the demo 14 seconds into the video you can see a big missing texture on the overhealed demo. I might've confused it with the pack that has the big green overheal cross?
You'd need to find and delete those particular texture(s) from your game files, but it's possible you can get this effect too. Not sure if sv_pure cares about that
any idea what files i'd have to delete?