Re: VDPAU Error: DISPLAY PRE-EMPTED
The VDPAU errors in comment #20 simply indicate that the overlay-based presentation queue could not be allocated. This probably isn't related to your issue.
Re: comment #21: VDPAU errors are printed to stdout and/or stderr. You should be able to redirect these to a file using:
command > logfile.txt 2>&1
where "command" is whatever you normally run.