When I was a kid, like books, movies were just one thing: something you watched in a “Movie Theater”. Then, with the advent of Television, we started to see “Movies made for TV”. Next we got movies we could both see in the theater and later rent of Beta or VHS tape to play on the home recorder (That you used to copy your favorite shows…). This was transformed into DVD and BlueRay media, and today you can hold the DVD you own in the cloud and play it on your phone. Streaming services provide access to your cloud storage as well as their own repositories. It has gotten to the point that for a few dollars a month you can get access to enough material to keep you glued to the screen 24/7, taking short breaks to eat and go to the bathroom. We have the technology to make you a true couch potato.
While movies started their existence without sound, you rarely find a movie today that has no sound (even the “Silent Movies” had piano music to accompany the visuals) and those old movies were all in “Black and White”, today’s movies have both sound and color. We even have movies presented in “3D”! Virtual Reality movies are just around the corner. So whether you saw it on YouTube or IMax it will likely qualify as a movie. Again, like books, there are some defining characteristics: it usually has a cast of characters, a director, a producer, a crew, and a host of assorted grips, makeup, and special effects/stunt coordinators; lasts from an hour or so up to maybe three hours and hopefully has some kind of story line.
A review of the worst movie you ever saw would probably serve the public interest at least as much, if not more, than a review of the best movie you ever saw. This does not mean you should avoid reviewing good movies.
Again, spoilers are at your discretion. Alluding to a plot twist at the end is not the same thing as completely explaining it. The first is not a spoiler, the second most certainly is.