It’s possible to get a virus from any data that enters your computer full stop.
Likelyhood wise: that virus on the MKV will have to attack the operating system preview system (which means you fucked all the way up to personal nation state attention), or attack the video player (which is a lot more likelier, they discover theoretical exploits all the time).
You’re talking about streaming with VLC? Was it a trusted source? Cause otherwise the FBI or script kiddie has probably fucked you up.