Yellow out is an ammonia based product. When you raise your pH to 8.0, add the product, and then shock the pool you form monochloramine, which is very effective at killing algae. Monochloramine is a nitrogen containing compound so the algae eats it as a food source and the chlorine content kills it. The problem is that after using a product like this you will find that you have no FC and all CC (that the monochloramine). It will take a few days to a week of sunlight and shocking to get rid of the monochloramine and have a FC reading but it does speed up the killing of the algae. I might speed the process of clearing a really green swamp but if your water is just a little green it's probably not worth it. IF you have mustard algae it might be useful, however, since mustard is hard to kill with straight chlorine.
The main caution I would give is to NOT overdose or the FC will be very difficult to recover. Once you treat just keep shocking with chlorine after and do not use a second dose.