Reddit users thevincentasteroid and MMD3_ posted about an auto-playing video ad (with sound) on the home screen. The ad is for Chicken Tender Wraps from Carl’s Jr. When it begins auto-playing, it pushes all the other UI elements out of focus and goes almost full-screen, returning to the home screen after it has played through once.
Since you started talking about iOS, do you actually mean the phone OS or ATV?
Because if phone OS: Since when were you able to sideload? Apple is still restricting it actively for all users and only now users in the EU will have the supposed option.