Is it illegal to stream a movie from a random server if I own a physical copy?
AFAIK it is. A local TV station in my hometown used to stream El Chavo del Ocho and El Chapulín Colorado from DVDs for a short while, even though the only TV network which had the streaming rights for those shows was SBT.
It's legal to view a film via any means if you own the license to that film. It's legal to backup a movie to which you own a license for, and it's legal to view the movie from backup.