To fit under 100MB, many "highly compressed" movies drop resolution from 1080p or 4K down to 480p or 360p , which reduces the number of pixels that need to be stored.
The "bitrate" is the amount of data processed per second. Reducing a 1080p video's bitrate from 10 Mbps to a much lower level (e.g., <1 Mbps) drastically cuts size but can lead to "blocky" or "smeared" images in high-action scenes. download highly compressed movies under 100mb work
Modern standards like H.265 (HEVC) and AV1 are the backbone of high compression. They are roughly 50% more efficient than the older H.264 standard, allowing for smaller file sizes at the same perceived quality. To fit under 100MB, many "highly compressed" movies