Safari 26.1 Fails to Play Attached MPEG-4 H.264 Video on macOS 26 and iOS 26.1

[fmaida]

Pre-submission Checklist

• I have searched the existing issues and this bug has not been reported yet
• I have tested this issue on the demo site or the latest version

Where did you encounter this bug?

Latest stable version (self-hosted)

Memos Version

v0.25.3

Bug Description

If I attach an MPEG-4 H.264 video to a post, it plays correctly on my Mac in both Firefox and Chrome.

However, when I load the same post with the attached video in Safari 26.1—whether on my Mac running macOS 26 or on my iPhone running iOS 26.1—the video cannot be played.

If you want to test it yourself, try visiting this page: https://cesco.blog/memos/kkQrnpjTgHvcwwHzVU4Dmc

Steps to Reproduce

1. Create a new post / note
2. Attach a mpeg-4 video to the post / note
3. Access the post / note with Safari

Expected Behavior

Videos that also work in Safari, at least when they’re in the MPEG-4 H.264 format that Safari handles without any trouble.

Screenshots & Additional Context