Omxplayer is a video player specifically made for the Raspberry PI's GPU made by forum user spenning. See the thread and download of omxplayer can be found here.
No rights to VCHIQ
On bare installations of the default distributions Omxplayer often has insufficient permissions to access /dev/vchiq. One solution would be to run omxplayer as root, but a nicer solution is to add a udev rule so that /dev/vchiq is also accessible from other users. To accomplish this, do the following under root:
# echo 'SUBSYSTEM=="vchiq",GROUP="video",MODE="0660"' > /etc/udev/rules.d/10-vchiq-permissions.rules
Now add yourself to the group named 'video':
# usermod -aGvideo USERNAME
Reboot the Raspberry and you should be able to run omxplayer without the vchiq-error showing up.
When using HDMI make sure to pass '-o hdmi' to omxplayer if you want the audio to playthrough the HDMI cable:
omxplayer -o hdmi videofile.mp4