Product Placement was brought to the forefront on the film, "ET." They use and mention Reese's Pieces. The way it works is this... When I get a job on a film (propmaster) I read the script and break it down for rentals, purchases, weapons and product placement. I get a copy of the script to product placement houses. These are companies with various "clients." one place could rep Miller beer and another company could rep MooseHead beer. If you buy an "LA 411" you'll be able to find the numbers of all the product placement companies. Let's say, we have a bar scene. The product placement agencies will place beer, neon signs, posters, t-shirts, etc in any one given scene. In essence, you need permission BEFORE you put something on the screen, otherwise you run the risk of getting sued. For instance, if you have a drug dealer using a Sony product in many scenes, that might be looked at as negative advertising. Conversely, if an "A-List" actor uses a boombox in a shot, often times, companies will PAY the production company to use their products as positive advertising. So, in your case, unless you find out who reps the particular product, it's always wise to turn labels, alter labels, use non-existant labels (that are created), or just use generic brands. Hope this helps.