MP4 attachment import may fail in new Media Picker

Summary

When importing large MP4 file using the new Media Picker in Jira when using the 'clip icon' on the issue view, the upload may fail, because:

• The file needs to be converted
• The browser needs to wait for the conversion, which may take several minutes in some cases

Steps to Reproduce

1. Try to attach a large MP4 file (replicated with a 40MB file) using the new Media Picker
   This cannot be replicated in Jira's old attachment upload tool, only in the new Media Picker

Expected Results

The file is uploaded

Actual Results

The file is not uploaded, the progress bar never finishes, though it reaches the end:

There's the 'Insert 1 file' in the window, but clicking it redirects us to the issue view page were the problem actually persists:

It won't finish and refreshing the page makes the attachment disappear (as it was never really attached).

This same problem happens across different instances with the same file.

We can see several 404 in Network tab in browser and errors in JS Console:

{"error":{"code":"NotFoundError","title":"The file with the given id does not exist","href":"https://api.media.atlassian.com#NotFoundError"}}

Workaround

It's possible to add the attachment in a comment. It doesn't fail when importing in a comment, even using the Media Picker.