A saved WebM video is different from a video playing on a website. Setting IINA as its local opener can make downloaded clips easier to watch without launching a browser. Test your file because codec support varies with the media.
Method 1: Use Finder
- In Finder, select a sample file such as download.webm.
- Press Command–I, or choose File → Get Info.
- Expand Open with and choose IINA. If it is missing, choose Other and locate the installed app.
- Click Change All and confirm the macOS prompt.
- Double-click another file of the same type to check the new default.
Method 2: Manage associations with Pahkui
Pahkui lets you browse by app or by format. When setting up an editor for several file types, you can inspect the current defaults and review pending changes in one window. Requires macOS 14 or later.
- Open Pahkui, switch to Format, and search for the extension you need from .webm.
- Select IINA. Use Choose another app if it is not listed.
- Review the pending association, click Apply changes, and confirm the new app in the macOS dialog.
The formats in this guide require Pahkui Pro, a one-time purchase for lifetime use. The manual Finder method does not require a purchase. See pricing
If the default app does not change
- Check that you downloaded the actual video, not an HTML page saved with a misleading filename.
- An unfinished .webm download may not play even if the correct app opens it.
- If IINA is missing, confirm it is installed and can open the sample directly, then locate it with Other. If an extension is absent from the catalog, add the format in Pahkui. Changing an association does not add format support to the target app.
Common questions
Does a WebM file default change my web browser?
No. It controls saved video files; the default browser for URLs remains unchanged.
How do I restore the previous app for .webm?
Choose the previous app again in Finder or Pahkui and confirm the change. This updates the type association without deleting files. Use the Open With context menu for a one-time exception.