Explanations for my tv? Resolutions.

I just bought a xbox one a few weeks ago. Having a lot of fun. I have a 720p tv and my settings are set to 720p. When I watch videos on youtube though it seems my screen is to small to fit the picture. I'm also playing sunset overdrive and it seems when I'm watching other youtubers play it, their screen guys more picture than mine:/

Submitted by TheGoldenFruit Xbox 720 Release Date 2015