They probably don't fall within the profile of x264 that the player can handle. Or it might also be some particular setting used when encoding. I'll put the
MediaInfo for each video so someone a little bit more in the know how of x264 can chime in. I know frequently that very high profiles like High @ 5.X, large amounts of reference frames, and large amounts of b frames usually aren't supported with most hardware decoders. It's because of this mess that I prefer to use a HTPC with a decent CPU to take care of the playback to avoid these issues, along with proper subtitle rendering.
Bad Videos
I Ain't Marryin' No Friggin' Horse!!!
Out of Control
Good Videos
RAH HEY!
Stupid Couple
The bad videos seem to fall into the too high of the settings I mentioned. I didn't find any specs of the files that the player can support on the site or in the manual. Most manufactures don't have this detailed information sadly. I'd either hook up a decent machine via HDMI or re-encode offending videos that you want to throw on a USB flash drive.
Insert clever text/image here.