Dear masters

Okay I recently bought a full hd Sony Bravia lcd and a Sony dvd player with hdmi output. I saved a normal quality video clip from youtube and plugged into the usb drive of the dvd player using my thumbdrive. Unfortunately, I didn't see any picture but there was sound. Then, I converted the clip into divx format and I got vice versa. However, the HD clip works completely fine.

Any thoughts ?