YouTube Video URL MIME Type

What does application/vnd.youtube.video-url mean?

application/vnd.youtube.video-url identifies a Poly bookmark whose destination is a YouTube video. It represents the link, not a downloaded copy of the video's audio and video streams. Poly uses the distinction to give the bookmark a video-specific thumbnail, player, metadata, and agent experience.

The type has no filename extension or magic number. A YouTube link can arrive through a pasted URL, a bookmark, or an imported desktop shortcut, but the URL itself is the useful identifying signal. Renaming a video file or an Internet Shortcut does not turn it into this type.

Is it an IANA-registered media type?

No. The current IANA media-type registry does not list application/vnd.youtube.video-url.¹ It is a product-specific identifier used by Poly and is not an official media type published by YouTube.

Its spelling follows the vendor-tree pattern defined by RFC 6838. The application top-level type describes data processed by an application, and the vnd. facet is used for publicly available products. A vendor-style name is not automatically registered. IANA registration is a separate review process.²

Poly repository history traces the type to 2025. The identifier remains in active use within Poly, but other applications should not be expected to recognize it.

What information does the link contain?

The bookmark's essential content is a YouTube video URL. Poly recognizes common YouTube watch links and shortened youtu.be links, extracts the video identifier, and presents the destination as one file-like item. The actual video stays on YouTube.

That separation explains the format's identification properties:

URLs can also include playlist, tracking, or playback-position parameters. Those parameters are not a substitute for the video identifier. When copying a link for long-term reference, keep the canonical video URL and retain a time parameter only when starting at a particular moment matters.

How to open an application/vnd.youtube.video-url item

Open it in Poly to play the destination in an embedded YouTube player. YouTube documents its standard single-video embed URL as https://www.youtube.com/embed/VIDEO_ID, and embedded playback can be customized with parameters such as a start time or caption preference.³

A web browser does not natively decode application/vnd.youtube.video-url. Outside Poly, open the destination URL itself in a browser or the YouTube application. Serving this MIME type as an HTTP response will not make a browser discover the destination because the type has no standardized payload syntax.

Playback depends on the hosted video. A removed, private, age-restricted, region-restricted, or embedding-disabled video may not play in the embedded view even if the bookmark remains in Poly. Opening the destination on YouTube may provide more context about the restriction.

Support in Poly

Poly turns supported YouTube URLs into useful items you can organize alongside files:

• Recognition: pasting or importing a supported video URL creates a YouTube-specific link rather than a generic web bookmark.
• Metadata and thumbnail: Poly shows the available video title, creator information, and thumbnail, which makes the link easier to recognize and find.
• Preview: opening the item uses an embedded player, so you can watch without leaving the file view when YouTube permits it.
• Search: the bookmark is searchable by its name and available video metadata. It does not receive an automatic searchable transcript or visual-similarity index.
• Agent use: the Poly agent can use an accessible video as context and can produce a transcript when asked. Reading can fail when YouTube does not make the video available.

These capabilities belong to the link item. Poly does not claim that saving the bookmark copies or preserves the hosted video. If the uploader deletes the video or changes its visibility, the saved destination can stop working.

How does it differ from bookmarks and video files?

Three related types can all lead to something that looks like a video, but they describe different objects.

A Windows .url file or macOS .webloc file is an interchange wrapper around a destination. Poly may recognize a YouTube destination during import and classify the resulting bookmark with application/vnd.youtube.video-url. The desktop shortcut's syntax is still different from the Poly media type.

Likewise, changing a downloaded .mp4 file's type to application/vnd.youtube.video-url discards useful information about what the bytes contain. Use a video media type for video bytes and this vendor type only for a Poly YouTube reference.

Can it be converted?

There is no ordinary media conversion because the source is a URL, not encoded video data. Choose an export based on the result you need:

• Copy the HTTPS destination when another application only needs the link.
• Export a desktop .url or .webloc bookmark when moving the destination between operating-system file managers.
• Use text/uri-list when a standards-based list of URI strings is appropriate.
• Download the video only when YouTube and the rights holder permit it, then keep the real container's MIME type and extension.

Converting the bookmark cannot guarantee preservation. A URL remains dependent on YouTube and the uploader, while a lawful downloaded file is a separate copy with different storage, rights, and update behavior.

Privacy, security, and availability

Treat a YouTube bookmark as an external network destination. Opening it contacts YouTube, and playback can disclose information such as the viewer's network address, browser data, and interaction with the player under the applicable Google and YouTube policies. YouTube specifically notes that enabling autoplay causes playback data collection and sharing to begin when the player loads.³

Before sharing a Poly item, check both the bookmark's title and its destination. Unlisted links are not private credentials, but anyone who receives the URL may be able to watch the video. Conversely, access to the bookmark does not grant access to a private video.