Startx over ssh to project images

[navise]

I have a Raspberry Pi 3 with a brand new arch install, to which I connect via SSH. The PI is conncted via HDMI to a projector, through which I can see a tty after boot.

I would like, through the SSH, to be able to start the X server and spawn a video. Reading online people suggesto to simply

$this->bbcode_second_pass_code('', '
ssh myserver
export DISPLAY=:0
startx
')

but I get a No Screens error.

The verbose log is

[url]
http://pastebin.com/WDpbXAx1
[/url]