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MP4 and OneNote Join Office and PDF as Supported File Types
Last year Microsoft added support for sensitivity labels with user-defined permissions in SharePoint Online, allowing the service to decrypt and process protected content. Until then, SharePoint Online could store files labelled with user-defined permissions, but couldn’t decrypt or encrypt the content, meaning that the content was unavailable for solutions such as Data Loss Prevention and eDiscovery.
Now, quietly and without an announcement or message center post, SharePoint Online has added OneNote and MP4 files to the set of fully supported formats. The development isn’t surprising because hints had been floated at events like Ignite 2025, but Microsoft didn’t make a formal announcement. The first hint that MP4 support was available was in the documentation describing how to protect Teams meeting recordings (and transcripts), which are stored in MP4 files in the meeting organizer’s OneDrive for Business account.
The Teams documentation pointed to information about how to enable SharePoint Online support for sensitivity labels applied to MP4 files (or as the documentation says, “video files”). The same documentation covers support for OneNote files. We’ll get to that in due course.
Enabling Support for Sensitivity Labels in SharePoint Online
Given the usefulness of sensitivity labels for protecting confidential information, you might be surprised that tenants must enable support for labels. It’s easy to switch on support for sensitivity labels by running the Set-SPOTenant cmdlet from the SharePoint Online management module (the command has been the same since SharePoint Online first supported sensitivity labels):
Set-SPOTenant -EnableAIPIntegration $true
Like most tenant-wide settings for SharePoint Online, it can take several hours before changes are effective. You’ll know when sensitivity labels are available within SharePoint Online when the browser UI reveals the option to apply labels to files.
Support for sensitivity labels allows SharePoint Online and OneDrive for Business to encrypt and decrypt file content so that files remain protected while service functions such as Microsoft Search indexing, eDiscovery, and Data Loss Prevention (DLP) continue to operate.
Selective Support for PDF, Video, and OneNote Files
After enabling sensitivity labels, you can move on to selectively enable support for PDFs, MP4, and OneNote files. By default, SharePoint Online can store but not process these file types, so if you want their content to be available to Purview solutions, you must enable support for each type. Once again, this is a matter of running the Set-SPOTenant cmdlet to update the parameters shown below.
For PDF files:
Set-SPOTenant -EnableSensitivityLabelforPDF $true
When sensitivity label support for PDFs is enabled, SharePoint Online and OneDrive for Business support PDFs labelled by Adobe Acrobat subscription products, PDFs exported from Word, Excel, or PowerPoint, and PDFs labelled outside Microsoft 365 with the Microsoft Information Protection (MIP) extension for Windows Explorer.
For OneNote files:
Set-SPOTenant -EnableSensitivityLabelforOneNote $true
OneNote supports sensitivity labels at the section level rather than at the notebook level. I’ve never been much of a OneNote user, but support is particularly important for education and research scenarios where notebooks often contain highly confidential information and have historically been difficult to govern consistently. Labels apply at the section level rather than a notebook, so cannot be applied through the SharePoint browser interface because it interacts with notebooks. Each section in a notebook can have a different label.
For Video Files:
Set-SPOTenant -EnableSensitivityLabelforVideoFiles $true
MP4 files don’t support automatic application of sensitivity labels or labels with user-defined permissions. When a sensitivity label with encryption is applied to an MP4 file (Figure 1), users cannot download the file from SharePoint Online. However, they can continue to view the content through the online viewers in SharePoint Online, Teams, and Clipchamp. The MP4 files generated for Teams meeting recordings (audio-only or audio and video) can inherit sensitivity labels from meeting settings.
According to message center notification MC1454399, Microsoft plans to extend support for video files to include Clipchamp project files (.clipchamp file extension). This change should be rolled out during September 2026.
Enabling support for a file type does not automatically label existing files or apply protection. Action must be taken to assign sensitivity labels through manual assignment (Microsoft 365 E3) or auto-labelling policies for PDF files (Microsoft 365 E5).
Another Way of Protecting Files
The Microsoft Purview Information Protection client has been available for Windows for several years to assign sensitivity labels to files stored outside Microsoft 365. The client is the successor of the Azure Information Protection client and adds the option to protect a file to the Windows File Explorer interface. I’ve used the client to protect many different types of files, including JPEG, PDF, MP3, and MP4.
According to message center notification MC1326509 (May 29, 2026), Purview is about to introduce File Labeler and File Viewer applications for MacOS to apply sensitivity labels to MacOS files and view the content of protected files (when permitted by the label). The applications are due to be available “on or around September 30, 2026.”
When the Information Protection client applies a sensitivity label with encryption to a file, the action depends on the file type:
- For Office and PDF files, the sensitivity label is stamped into the file metadata. This is what happens when SharePoint Online or OneDrive for Business assigns a label.
- For other file types, the client creates a rights management protected file that can only be opened by a viewer, like the viewer integrated into the Windows client or the separate MacOS application. Figure 2 shows the properties of a PowerShell script file (.PS1) which is protected by a label.
Essentially, a secure wrapper protects the file. You can upload protected files into SharePoint Online or OneDrive for Business, but the content cannot be decrypted and is therefore unavailable to Purview solutions. Now that SharePoint Online supports MP4 files, less of a need exists to use the Information Protection client.
Office files, PDFs, OneNote, and now MP4 files cover a large proportion of the content stored in SharePoint Online and OneDrive for Business. Whether Microsoft sees enough demand to justify support for additional file types is another question.
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