Why your saved video has no sound, and how to fix it
A silent download almost always means you grabbed the video track on its own. The audio was never missing, it was simply stored somewhere else.
Separate streams, one file
Modern players do not stream one combined file. They pull a video track and an audio track at the same time and line them up as they play. Your browser shows one player, but there are two downloads happening behind it.
Right click and save, or a simple grabber extension, takes the first thing it finds, which is the picture. That is the whole mystery.
Reddit is the worst offender
Reddit splits every hosted video this way, which is why so many saved Reddit clips are silent. The audio sits at a sibling address that a naive save never touches.
Use the file marked with sound and the two tracks are already joined before the download starts.
X, Instagram and the muted upload
Sometimes there really is no audio. Plenty of clips are uploaded muted, and animated GIF style posts on X have no audio track at all by design, because they are short videos pretending to be GIFs.
If the post plays silently in the app with the volume up, the download will be silent too, and no tool can invent the missing track.
Quick checks before you blame the downloader
Play the original with your ringer switch off and volume up. Phones mute autoplay aggressively.
Open the saved file in a real player rather than a preview thumbnail. Some file previews do not decode audio.
Check the file size. A silent minute of video is usually a couple of megabytes lighter than the same clip with sound.