From raspberrypi forum, you can use tvservice:
Run “tvservice -m CEA” to give a list of CEA supported modes.
Run “tvservice -m DMT” to give a list of DMT supported modes.
Run “tvservice -s” to give you the current state.
Alternatively you can do the following:
1. Run “tvservice -d <file>” to capture a monitor’s EDID.
2. Pass ...
Unfortunately it seems that as of November, 2019, this cannot be done.
It can definitely multi-display using the same protocol/driver, however it can't do it if you are using DSI + HDMI.
The issue is that the underlying boot code enables a framebuffer to HDMI or a framebuffer for DSI, but not both.
There are TFT screens that actually have HDMI / mini ...
VLC is getting custom (downstream !) patches for the Raspberry Pi all the time. The foundation pays experienced developers to create and test them. Obviously, without running the latest software you will not see any of it.
VLC uses software decoding without these patches, and will be very slow.