If you have ever downloaded a video that refused to play, the file format was probably the reason. In short: MP4 is the safest choice for video because almost every phone, computer and TV can play it, MP3 is the universal choice when you only want the sound, and WebM is a web-friendly format that plays well in browsers but less reliably in some built-in apps. This guide explains why, without the jargon.

Containers and codecs: the box and what is inside

A video file has two layers, and mixing them up causes most of the confusion.

• The container is the box. It is what the file extension tells you: .mp4, .webm, .mov, .mkv. The box holds the video track, the audio track and some information such as duration and orientation.
• The codec is the way the picture and sound inside the box were compressed. Common video codecs are H.264, H.265 (HEVC), VP9 and AV1. Common audio codecs are AAC, Opus and MP3.

This is why two files that both end in .mp4 can behave differently. One may contain H.264 video, which plays almost everywhere, while the other contains H.265, which needs newer hardware or extra software on some computers. To play a file, your device has to understand both the box and the codecs inside it.

The formats you will actually meet

MP4

MP4 is the most common video container in the world. It usually holds H.264 or H.265 video with AAC audio. An MP4 with H.264 and AAC is close to universal: it plays on iPhone and iPad, Android, Windows, Mac, smart TVs, game consoles and in every modern browser. It also opens in practically every video editor, which makes it the best format for keeping and reusing your own clips.

WebM

WebM is an open format designed for the web. It typically contains VP9 or AV1 video with Opus audio. Every major desktop browser plays WebM, and Android handles it well. Support in some built-in apps is weaker: the iPhone Photos app and QuickTime Player on the Mac, for example, may not open a WebM file even though Safari can play it. If you plan to put a video in your phone's gallery or edit it, MP4 is the easier choice.

MOV

MOV is Apple's container and is what an iPhone camera produces. Inside it is usually H.264 or H.265 video. It plays without trouble on Apple devices and in most modern players elsewhere.

MKV

MKV (Matroska) is a flexible container that can hold almost any codec and several audio tracks. It is popular for archiving, but many phones and TVs do not play it out of the box.

GIF

A real GIF is an old image format: no sound, a limited palette of 256 colors and large file sizes. Most "GIFs" you see on social platforms today are actually short, silent MP4 videos set to loop, because MP4 is far smaller and sharper. When you save one, you will usually get an MP4 file. Our guide to downloading X (Twitter) videos and GIFs explains this in practice.

MP3 and other audio formats

MP3 is the best-known audio-only format. Every phone, computer, car stereo and smart speaker can play it. Its quality depends on the bitrate: 128 kbps is fine for speech, while 192 to 320 kbps keeps more detail in music. You may also come across M4A files, which are AAC audio in an MP4-style container, and Opus, which is very efficient but less widely supported by older devices.

What plays where

Here is a practical summary for each type of device. "Built-in" means the apps that come with the system, without installing anything.

• iPhone and iPad: MP4 (H.264 and H.265), MOV and MP3 play in the Files app and can be saved to Photos. WebM plays in Safari on recent versions of iOS, but is not reliably accepted by the Photos app.
• Android: MP4, WebM and MP3 play on virtually all current phones in the built-in gallery or video player. H.265 depends on the phone's hardware, though most phones from the last several years support it.
• Windows 10 and 11: MP4 with H.264 and MP3 play in the built-in Media Player. H.265 may need Microsoft's HEVC Video Extensions from the Microsoft Store. WebM plays in every browser.
• Mac: MP4, MOV and MP3 play in QuickTime Player and the Music app. H.265 is supported on recent macOS versions. WebM opens in Safari and other browsers, but not in QuickTime Player.

If a file will not play in a built-in app, try opening it in your browser by dragging the file into a browser window, or use a free general-purpose media player such as VLC, which handles nearly every container and codec.

Video file or audio only: how to decide

Choose a video file (MP4) when the picture matters: tutorials that show steps on screen, clips of your own you want to edit or re-share, or anything you will watch on a TV.

Choose MP3 when only the sound matters. Typical examples are a recording of your own talk, a voice note you posted, a lecture you have permission to keep, or an interview you were part of. An MP3 is a fraction of the size of the video and plays in any music or podcast-style app in the background with the screen off. For a closer look, read our guide to extracting audio from a video as MP3.

Whichever you choose, only save content you own or are allowed to use, and do not re-upload other people's work. Our copyright page explains what that means in practice.

How VidGrabo handles formats

1. Copy the link of a public video from TikTok, Instagram, Facebook, X (Twitter) or Pinterest.
2. Paste it on VidGrabo in any browser, on your phone or computer. No sign-up or app is needed.
3. Pick a video quality to get the video file, or pick MP3 to save only the audio.
4. The file downloads to your device. On iPhone it lands in the Files app under Downloads; on Android it goes to Downloads or appears in the Gallery.

The qualities you see depend on what the original upload provides; VidGrabo never upscales. Private or login-only videos cannot be downloaded, and you can save one video link at a time.

Frequently asked questions

Is MP4 better quality than WebM?

Not by itself. The container does not decide quality; the codec and bitrate do. A WebM with VP9 and an MP4 with H.265 can look equally good. MP4 simply plays on more devices and apps.

Can I convert an MP3 back into a video?

No. An MP3 contains only sound, so the picture is gone. If you might need the video later, save the video file and keep the MP3 as an extra.

Why does my MP4 play on my phone but not on my Windows PC?

The file is most likely encoded in H.265 (HEVC). Install Microsoft's HEVC Video Extensions, play it in a browser, or use a media player that includes its own decoders.

Does converting a file to another format improve quality?

No. Converting can only keep quality the same or reduce it, because each re-encode throws away a little more detail. Start from the best version you can get.

Conclusion

Think of the container as the box and the codec as the way its contents were packed. For video, MP4 with H.264 is the safest bet on every device; WebM is fine for browsers and Android; MP3 is the right choice when only the voice or sound matters. To understand how resolution and bitrate fit into the picture, see our explainer on video quality from 360p to 4K, or head to the VidGrabo home page to save a public video in the format that suits you.