videos pixellated

Hi, I have a BIG problem with my videos..

I don't know hot to explain, but during editing and also after exported my video I noticed that there are some pixels as big as my head, and the quality is awful.

here's a screenshot:

[img]http://s15.postimg.org/8fzvrq2fv/Schermata_2015_02_06_alle_23_11_52.png[/img]

I record my videos with a reflex, Nikon D5100, and I don't know if it's a camera, SD, mac or program problem (I'm using Final Cut Pro X), but I really don't know what to do.. I had the same problem with another compact camera and with iMovie.

I need to upload HD videos on my channel, since they are about makeup and most of them are close-ups, and this problem it's very annoying.

I hope some of you can help me 😟

Thanks!