Vid-20220418-wa0011mp4 «EASY»

"Proper paper" in the context of slinging.org likely refers to:

I cannot play the video to confirm, but I suggest checking the slinging.org forum for the thread matching that attachment name for the exact context, as attachments there often depict experiments with different materials. VID-20220418-WA0011mp4

Documentation or instructions referenced within the forum attachments, potentially describing the use of a "proper" projectile. "Proper paper" in the context of slinging

Based on searches, the file VID-20220418-WA0011.mp4 appears to be a video attachment in the slinging.org forum . This community often discusses creating, using, and repairing slings. and repairing slings.