Originally Posted by Sleeb
Which aspect ratio should I be converting the videos to then?
It always depends on the source video and your usage.
Now that you know the maximum this sony can play, you can still restrict yourself to the device screen size:
4:3 movie --> 640x480 px
16:9 movie --> 720x405 px
I've just downloaded a movie trailer at 640x268px, so roughly 2.4:1 ratio. For this geometry, with a bigger source movie your conversion would be:
2.40:1 movie --> 720x300 px
And so on... Beware that there are often differences between pixel ratio and output ratio. A 16:9 widescreen PAL DVD movie at 720x576 px is 1.25:1, but must be shown at 1024x576 px (16:9). So you must take this output ratio in account when converting. Sometimes you have movie whose ratio is 2.40:1 on a 16:9 presentation, where the black bars are already added. You just have to play it at the 16:9 ratio.