This page covers the "How to make money in GTA 5 (Stock Market Guide)" video by GTA Series Videos. Based on the title and snippet, it appears to be a tutorial for the single-player story mode stock market, not GTA Online. The video likely explains how to use Lester's assassination missions to manipulate stock prices for huge returns on your character's cash.
This is a legitimate, intended game mechanic, not a glitch. It should still work in single-player as designed. There is no ban risk for using the stock market; Rockstar built this system into the story. However, always verify the video's upload date and read recent comments to confirm the specific steps still match the current game version. Patches for single-player are rare, but updates can sometimes change mission details. Check the video's current working status before you invest your in-game cash.
