Avic D3 and youtube videos

[2amlogic]

Hello everybody! I recently installed an Avic D3, and I'm trying to put together a collection of youtube videos on DVD to play in the unit. My problem arises when the video is played on the unit, the image is too small. When I'm converting the file from youtube, I'm setting the resolution at 500x240 which is supposed to be the correct resolution, but it still goes small on me. Has anyone done this successfully? My regular movies and such play fine, and I'm setting it as Windows DIVX/AVI. Sorry for such a "non-important" question, but it's bugging me, and I'm sure you all can feel my pain