This isn't possible.
A DVD player (or more precisely, a DVD-Video player) will only play video that is compiled into the DVD-Video format, which is very specific and has narrow specs. Without going into too much detail, DVD-Video is based on MPEG-2 compression, PCM or AC3 or DTS or MPEG Layer II audio, and both audio and video have very rigid minimums and maximums for allowed bitrates and other internal codec settings (example: GOP length). It's authored to 1GB VOB sets with IFO nav data, inside a specific folder structure (VIDEO_TS).
At best, some DVD players will allow you to play more video formats, such as WMV or AVI (Xvid and DivX codecs only). Take a look at the Philips models of DVD players. Specifically, at the time of this post (March 2011), look at the
Philips DVP3560/F7 DVD Player with 1080p HDMI Upscaling and Multimedia DiVX that's available for
$72 shipped from Amazon.com.
Another option is to avoid DVD players entirely, and go for one of the small "media center" devices, such as the Western Digital WDTV (
$69 shipped from Amazon) or the WDTV Plus (
$94 shipped from Amazon). The WDTV will play most AVI, MKV, MPEG files, plus several others. The WDTV Plus adds a few more file type and codec choices, such as ISO files (aka "DVD rips").
That's really your only option for playing non-DVD-Video files as is, without conversion, on a TV.