Because H.265 is more computationally intensive than older formats, you need the right tools to play them without draining your battery or causing lag:

When you look for 100MB HEVC movies, you are entering the world of "micro-encodes." To achieve such tiny sizes, encoders typically downscale the resolution to 480p or a "optimized" 720p. They also utilize AAC or Opus audio codecs, which provide clear sound at very low bitrates. While these files won't satisfy a home theater enthusiast with a 75-inch OLED, they are remarkably crisp on tablets and phones, offering a smooth, stutter-free experience. How to Play HEVC Files

As we move toward even newer standards like AV1, the "100MB movie" trend will only improve. We are reaching a point where the physical size of data is no longer a barrier to accessing the world's most popular films. For those who prioritize portability and accessibility over raw bitrate, the HEVC revolution is the ultimate win for global entertainment.