Videos are turning out grainy

[AtlasXLII]

Hey guys, total noob at video stuff. I'm using a nikon p520 (not the best but it's what I got handy) and every video I record turns out grainy when I put it on my computer. I'm using the 1080 30p settings. I don't know if it is just the camera or if it's bad lighting because most of what I record is inside. If anyone has any suggestions I would appreciate it. Thanks

[smrpix]

Grain (more accurately "noise" since this isn't film) is usually a result of insufficient light, the chip tries to amplify what's there. Post a short original clip if you want folks to take a look.