Default 1080p mkv black screen, only audio...wut??

whaaaatsup guys, I have a question for you all kind people that will help me
I have a mkv "the hobbit 2" 1080p and wanted to see how does my fantastic phone handle a full resolution video...u know, see all these little pixels used as they should...I am a big fan of images and screen quality!'s like an orgasm

SO, copied the file, downloaded vlc (the best) and.....only audio! black screen...what?

another case: I watched a 1080 video on dailymotion (web) and same, black screen only audio...

what's wrong?? any help?
flash veteran

HTC One M7ul silver 32Gb
Nexus 7 (2013) Flo WiFi 16Gb