[mythtv] Video Capture Mode

[Jeremy Oddo]

Does anyone know what video capture mode MythTV uses?  Here's why I ask: 
I see picture fine at 320x240 res, but if I bump it up to say 640x480 this
weird shifted over picture (it almost looks like the picture starts midway
thru the frame (vertically) then wraps around to the other side).  I
noticed that if I go into xawtv and enlarge the window the picture looks
fine, but if I switch the capture mode from "overlay" to "grabdisplay" it
does the same thing.

Is there a setting to get around this?