: This indicates the resolution . Lenovo defines 720p as High Definition (HD) with a frame size of 1280x720 pixels. The "p" stands for progressive scan, which means the image is drawn line-by-line for smoother motion.
: If you use a video downloader, it often saves files with these numeric tags to avoid name conflicts. 172_720p.mp4
: This is the file container . According to Adobe , MP4 is the industry standard because it balances high-quality video with relatively small file sizes, making it ideal for web streaming. Common Contexts for this Filename: : This indicates the resolution