Such a device exists

[scherzo]

It sounds like you are trying to do this (correct me if I'm wrong)

You have media files on your computer (movies... By the sounds of it since you are burning .avi files)

You want to put them on a USB drive then walk over to the tv and play the files.

You could get rid of the USB portion by using an apple tv.

As long as you have iTunes installed on your computer you can play any media files in your library (stored on your computer) and stream it to your tv.

You could also do the same thing if you have windows 7 and an Xbox 360.

$129 for an Xbox
$119 for an apple tv

I have both but like the interface on the apple tv. It seems peppier than browsing media on the 360.