Basketball is truly a game of inches. Every movement matters, every situation requires a meticulous attention to detail and perfect execution. NBA players, college players, and even elite high school players are adept at all of this, which is why they are at the level that they are. So, if you're trying to expand your skill set, why not learn from these players?
Here's where Non-Conscious Behavior Mimicry comes in. Essentially, this phenomenon states that when one observes another do something enough, they will eventually mimic it, without even knowing it (citelighter.com). This is why many sons and fathers share characteristics, but also why many basketball players shoot, dribble, or make decisions similar to their favorite players'. So, if just by watching great players play enough, you could "mimic" their play and thus slightly improve yours, why wouldn't you?
This is just one of the many benefits of watching film. Granted, you cannot significantly improve your skills by watching a screen, however you can gain a huge advantage. By watching film of high-level players--and not just watching for highlights; you must actually study every second--you can understand how these players have gotten successful. Looking at their footwork, body positioning, decision making, how they set up moves, defensive positioning, what tricks they use to get steals, and so much more.
There are two main ways to do this. First is watching full games. We understand, however, that this is time-consuming, and the games that you do sit down and watch in their entirety are generally big games that you would like to watch from a fan's perspective. If you are willing to study each movement during Game 7 of the NBA Finals, then great. That's a huge advantage. If you would rather watch from a fan's perspective, at least attempt to watch replays of games (or even quarters of these games), because full games, unlike highlights, show the entire story. In fact, many times mistakes, mundane plays, and defense are just as beneficial to watch as the top plays, because these are the things that truly separate the good and the great. This is also why teams and players should watch their own games (especially losses or poor games). It is much easier to correct a mistake in the future when one has a full, clear idea of what they have done and how to fix it (Which is hard to come by without watching yourself fail. It's easy to watch yourself when you look good!)
If you do not have enough time to watch the entirety or parts of full games (by the way, summer league games, matchups between mediocre NBA teams, and mid-major college games are just as beneficial if not more, because there are players similar to the majority of the basketball population), highlights still are undoubtedly beneficial. Just make sure you are watching for the right things...
How to Watch Film
First, realize what/who you are watching. Know what each player or team does well, or does not do well. For example, if you're watching a Michigan State team, realize how well they rebound (generally). If you're watching Tyler Ulis Kentucky film, understand prior to watching how well he changes pace and controls the game. If you're watching Stephen Curry, know to look for how he reads the defense and uses his body to get to his shots.
Next, as you begin to watch, break down each play in your mind or in notes. Go through plays in slow motion. Watch players' feet, body positioning, and decision making over and over again. Then, analyze it. What situations do they make certain decisions in? How could they improve something? How could you implement it into your game? Or, if it is your film, how could YOU improve?
Really, from there, there are many possibilities. You can keep track of certain shots or plays in a notebook or shot chart, such as the one below of Kyrie's shot chart in the finals...
Resources For Watching Film
NBA Game Highlights/Compilations: www.youtube.com/channel/UCEjOSbbaOfgnfRODEEMYlCw
College Highlights/Compilations: www.youtube.com/channel/UC2ZtDh_fAYM4UYzg-xD-t9w/videos
NBA TV (Summer league, replays of vintage games and playoff games, etc)
Highlights for non-superstar players/compilations: www.youtube.com/user/DownToBuck/videos
Krossover/Hudl as team highlights resources