I've downloaded a few games, (skyrim, league, sims 3) and it gets hot which is normal. But when I search and watch videos 15 minutes later the fan becomes louder and I can feel it getting hotter. Its not too hot and the fan doesn't sound abnormal. If I put my ear 5 inches from the fan i can hear it clearly.
Sometimes the fan gets louder when i watch videos or start searching. Its erratic. Anyways the laptop is about 1 month old and its a Lenovo G505S. AMD 10 and 6 RAM.
Simply your machine, like almost all laptops, does not have the necessary ventilation needed. You can try a cooling pad to add in keeping it cool, but even they do not work all the time.
Mine got so hot that the battery door latch melted.
"Cooling Pads", "Chilling Pad" are a good start. Some power from the wall, others from the laptop USB port.
Sounds like your fan intake might be slightly blocked. Never sit laptops on beds, sofas, clothing or anything material. The fan will suck in fibers eventually affecting how well the cooling system operates. I would take it to a qualified technician to open it up and clean out the fan.
You can take it to a technician and clean the laptop fan. You can do it yourself also. The best thing you can do that, contact with the service provider of your laptop.