Canon T5i video VERY grainy?

Even at ISO 200, my video is very grainy and pixelated, primarily in the darker spots, but I've seen nice videos with this camera, but when I set my shutter speed to 1/30th, quality to 1920x1080 30fps, aperture 3.5 and ISO 200, it still looks like crap! I'm getting really discouraged because I bought this camera for video and pictures, and I wanted to use it for a YouTube channel, but the footage is grainy and unusable!!! Please help, I hate dealing with all this. I bought it used on Amazon a couple months ago, but this is just crap video. Even in moderate light, the darker spots still look like crap!

 

If the exposure is not accurate, particularly if video/still images are under exposed, few DSLR cameras can make videos/images free of noise.

Photographer/videographer knowledge and skill is still required to make acceptable video with any DSLR camera.

 

Maybe you need to add some lights to the scene if possible.