First of all: If you are interested in picture quality, don't view commercial movies. They are outright aweful. Low FPS, motion blur, noise etc. pp.
Such a movie should never be considered a viable source to measure a display. Amateur movies often pay a lot more attention to good quality. Same as games. Use them.
Watching movies from a PC has been the standard way to do it since about 20 years now. It's also viable, especially if you look for quality. Calibrating the screen correctly (white blance, gamma etc.) is also something that has to be done. Most TVs are set up wrong so that the signal is cropped and scaled, introducing more artifacts. Every time I arrive at a hotel and want to watch something, I have to go through the whole programme.
At home I use a HTPC and a 50" Plasma since 2012 - never had any problems with it.
