[Mount81]

I'm interested in purchasing a Zidoo. Probably the x9s. Somewhere I read it has issues with playing smooth when playing movies encoded with VP9. Is that issue ISO, MKV or 3D specific? I plan to only use it to play 3D movies. If it affects 3D movies, is there a list of 3D movies that are encoded with the VP9 codec? The only VP9 movie I have found in my library so far is The Dark Knight, which obviously isn't 3D.

I would not think that there are or will be any 3D movies encoded in VP9.
It's mostly used by Google on YouTube, not even 2D FHD or UHD BD's would be in VP9. 
But for contents available on YT I guess you will still need it.